A: The common notation for the "intercept" term of an equation specified as Y = a + bX. Mathematically, the a-intercept term indicates the value of the Y variable when the value of the X variable is equal to zero. Theoretically, the a-intercept is frequently used to indicate exogenous or independent influences on the Y variable, that is, influences that are independent of the X variable. For example, if Y represents consumption and X represents national income, a measures autonomous consumption expenditures.

A Posteriori: A conclusion reached through logical reasoning based on facts and observations about the real world. This notion is closely related to the scientific verification of hypotheses and the identification of principles. A similar sounding, but opposite term is a prior, which is a unverified presumption made before an analysis is undertaken. For example, in the study of economics of crime you might assume, a priori, that people are basically "good", and conclude, a posteriori, that people are more likely to commit crimes when the threat of capture and conviction is lower.

AAUP: The abbreviation for American Association of University Professors, which is an association of university and college faculty established in 1915 to protect academic freedom. The AAUP is the closest thing university faculty have to a labor union. While it does engage in some collective bargaining functions with specific universities, similar to traditional labor unions, its primary function is to ensure that faculty maintain intellectual or academic freedom from political of social pressures.

Ability-to-Pay Principle: A principle of taxation in which taxes are based on the income or resource-ownership ability of people to pay the tax. The income tax collected by our friends at the Internal Revenue Service is one of the most common taxes that seeks to abide by the ability-to-pay principle. In theory, the income tax system is set up such that people with greater incomes pay more taxes. Proportional and progressive taxes follow this ability-to-pay principle, while regressive taxes, such as sales taxes and Social Security taxes, don't.

Absolute Advantage: The general ability to produced more goods using fewer resources. This idea of absolute advantage is important for trading that occurs between both people and nations. A nation can get an absolute advantage from an advanced level of technology or higher quality resources. For a person, an absolute advantage can result from natural abilities or the acquisition of human capital (education, training, or experience).

Absolute Poverty: The amount of income a person or family needs to purchase an absolute amount of the basic necessities of life. These basic necessities are identified in terms of calories of food, BTUs of energy, square feet of living space, etc. The problem with the absolute poverty level is that there really are no absolutes when in comes to consuming goods. You can consume a given poverty level of calories eating relatively expensive steak, relatively inexpensive pasta, or garbage from a restaurant dumpster. The income needed to acquire each of these calorie "minimums" vary greatly. That's why some prefer relative poverty.

Absolute Poverty Level: The amount of income a person or family needs to purchase an absolute amount of the basic necessities of life. These basic necessities are identified in terms of calories of food, BTUs of energy, square feet of living space, etc. The problem with the absolute poverty level is that there really are no absolutes when in comes to consuming goods. You can consume a given poverty level of calories eating relatively expensive steak, relatively inexpensive pasta, or garbage from a restaurant dumpster. The income needed to acquire each of these calorie "minimums" vary greatly. That's why some prefer a relative poverty level.

Abstraction: Simplifying the complexities of the real world by ignoring (hopefully) unimportant details while doing economic analysis. Abstraction is often criticized because it's, well, it's JUST NOT REALISTIC. However, when done correctly (ignoring things that JUST DON'T MATTER), then the pursuit of knowledge is greatly enhanced by abstraction. For example, when travelling cross country along a high-speed interstate highway, a paper road map is a handy tool. It shows towns and cities along the way, the major intersections, rest stop locations, and other important points of interest. However, it ignores unimportant details. It doesn't realistically show the location of every tree, bush, or blade of grass. Why bother? This information won't enhance your road trip.

Abstraction Methods: Abstraction is the process of simplifying the complexities of the real world by ignoring (hopefully) unimportant details, especially (for our purposes) while doing economic analysis. Three common methods of actual, real world abstraction used in economic theories are words, graphs, and equations. Words can be misunderstood. Graphs are a little more precise. And equations tend to be the most precise of the three.

Accelerator: The ratio between investment expenditures and the change in gross domestic product. This is based on the notion that business investment depends on the rate of growth of aggregate output. If the economy is expanding, in other words, then the business sector invests in more capital goods to produce the extra output needed. This accelerator effect modifies and magnifies the simply multiplier effect based on the induced consumption and the marginal propensity to consume.

Accessibility: The location of economic activity (especially in terms of land) relative to other activities. As real estate agents are prone to say, "The three most important factors in real estate are 'location, location, location.'" Accessibility determines how easy or difficult (read this as costly) it is to allocate good, services, and resources. Transportation is a key factor in accessibility. Efficient, low cost transportation systems improve accessibility.

Accounting Cost: The actual outlays or expenses incurred in production that shows up a firm's accounting statements or records. Accounting costs, while very important to accountants, company CEOs, shareholders, and the Internal Revenue Service, is only minimally important to economists. The reason is that economists are primarily interested in economic cost (also called opportunity cost). That fact is that accounting costs and economic costs aren't always the same. An opportunity or economic cost is the value of foregone production. Some economic costs, actually a lot of economic opportunity costs, never show up as accounting costs. Moreover, some accounting costs, while legal, bonified payments by a firm, are not associated with any sort of opportunity cost.

Accounting Profit: The difference between a business's revenue and it's accounting expenses. This is the profit that's listed on a company's balance sheet, appears periodically in the financial sector of the newspaper, and is reported to the Internal Revenue Service for tax purposes. It frequently has little relationship to a company's economic profit because of the difference between accounting expense and the opportunity cost of production. Some accounting expense is not an opportunity cost and some opportunity cost is does not show up as an accounting expenses.

Activist Policy: Government policies that involve explicit actions designed to achieve specific goals. A common type of activist policy is that designed to stabilize business cycles, reduce unemployment, and lower inflation, through government spending and taxes (fiscal policy) or the money supply (monetary policy). Activist policies are also term discretionary policies because they involve discretionary decisions by government. A contrast to activist policy is automatic stabilizers that help stabilize business cycles without explicit government actions.

Action Lag: In the context of economic policies, a part of the implementation lag involving the time it takes for appropriate policies to be launched once they have been agree to by policy makers. Another part of the implementation lag is the decision lag. For fiscal policy, this involves appropriating funds to government agencies (for government spending) or changing the tax code (for taxes) For monetary policy, this involves the buying and selling government securities in the open market. The action lag is usually shorter for monetary policy than fiscal policy.

Actual Investment: Investment expenditures that the business sector actual undertakes during a given time period, including both planned investment and any unplanned inventory changes. This is a critical component of Keynesian economics and the analysis of macroeconomic equilibrium, which occurs when actual investment is equal to planned investment. The difference between planned and actual investment is unplanned investment, which is inventory changes caused by a difference between aggregate expenditures and aggregate output. Should actual and planned investment differ, then aggregate expenditures are not equal to aggregate output, and the macroeconomy is not in equilibrium.

Accumulation: The process of acquiring a item and adding that item to others previously acquired. In an economic context this most often refers to the accumulation of capital, as in the phrase "capital accumulation." However, it is also used in the context of consumer durable goods, financial assets, money, wealth, and a host of other "stock" variables. When applied to capital, the process of accumulation occurs through investment.

Activist Policy: Government policies that involve explicit actions designed to achieve specific goals. A common type of activist policy is that designed to stabilize business cycles, reduce unemployment, and lower inflation, through government spending and taxes (fiscal policy) or the money supply (monetary policy). Activist policies are also term discretionary policies because they involve discretionary decisions by government. A contrast to activist policy is automatic stabilizers that help stabilize business cycles without explicit government actions.

AD: The abbreviation for aggregate demand, which is the total (or aggregate) real expenditures on final goods and services produced in the domestic economy that buyers would willing and able to make at different price levels, during a given time period (usually a year). Aggregate demand (AD) is one half of the aggregate market analysis; the other half is aggregate supply. Aggregate demand, relates the economy's price level, measured by the GDP price deflator, and aggregate expenditures on domestic production, measured by real gross domestic product. The aggregate expenditures are consumption, investment, government purchases, and net exports made by the four macroeconomic sectors (household, business, government, and foreign)

AD-AS Analysis: An economic model relating the price level and real production that is used to analyze business cycles, gross domestic product, unemployment, inflation, stabilization policies, and related macroeconomic phenomena. The AS-AD model, inspired by the standard market model, captures the interaction between aggregate demand (the buyers) and short-run and long-run aggregate supply (the sellers).

AD-AS Model: An economic model relating the price level and real production that is used to analyze business cycles, gross domestic product, unemployment, inflation, stabilization policies, and related macroeconomic phenomena. The AS-AD model, inspired by the standard market model, captures the interaction between aggregate demand (the buyers) and short-run and long-run aggregate supply (the sellers).

AD Curve: The aggregate demand curve, which is a graphical representation of the relation between aggregate expenditures on real production and the price level, holding all ceteris paribus aggregate demand determinants constant. The aggregate demand, or AD, curve is one side of the graphical presentation of the aggregate market. The other side is occupied by the aggregate supply curve (which is actually two curves, the long-run aggregate supply curve and the short-run aggregate supply curve). The negative slope of the aggregate demand curve captures the inverse relation between aggregate expenditures on real production and the price level. This negative slope is attributable to the interest-rate effect, real-balance effect, and net-export effect.

AD Valorem Tax: A tax that is specified as a percentage of value. Sales, income, and property taxes are three of the more popular ad valorem taxes devised by government. The total ad valorem tax paid increases with the value of what's being taxed

Adjustment, Long-Run Aggregate Market: Disequilibrium in the long-run aggregate market induces changes in the price level that restore equilibrium. If the price level is above the long-run equilibrium price level, economy-wide product market surpluses cause the price level to fall. If the price level is below the long-run equilibrium price level, economy-wide product market shortages cause the price level to rise. In both cases long-run equilibrium is restored. Price level changes induce changes in aggregate expenditures but NOT changes in real production. The reason is that long-run aggregate supply is full-employment real production, which is unaffected by the price level.

Adjustment, Short-Run Aggregate Market: Disequilibrium in the short-run aggregate market induces changes in the price level that restore equilibrium. If the price level is above the short-run equilibrium price level, economy-wide product market surpluses cause the price level to fall. If the price level is below the short-run equilibrium price level, economy-wide product market shortages cause the price level to rise. In both cases short-run equilibrium is restored. You might want to compare adjustment, long-run aggregate market. Price level changes induce changes in both aggregate expenditures and real production. Unlike the long-run aggregate market, changes in the price level can induce changes in short-run aggregate supply, making it greater or less than full-employment real production.

Adverse Selection: When a negotiation between two people with different amounts of information, that is, asymmetric information, restricts the quality of the good traded. This typically happens because the person with more information is able to negotiate a favorable exchange. This is frequently referred to as the "market for lemons."

Advertising: Information provided about a product by a company to promote or maintain sales, revenue, and or profit. Advertising is often an explicit method of signalling that sellers use to provide information to buyers. The primary objective of advertising from the sellers perspective is to increase (or at least maintain) demand for a product. To accomplish this objective advertising provides buyers with two important types of information -- prices and product quality.

AE Line: Another term for aggregate expenditure line, which is a line representing the relation between aggregate expenditures and gross domestic product used in the Keynesian cross. The aggregate expenditure line is obtained by adding investment expenditures, government purchases, and net exports to the consumption line. As such, the slope of the aggregate expenditure line is largely based on the slope of the consumption line (which is the marginal propensity to consume), with adjustments coming from the marginal propensity to invest, the marginal propensity for government purchases, and the marginal propensity to import. The intersection of the aggregate expenditures line and the 45-degree line identifies the equilibrium level of output in the Keynesian cross.

AEA: The abbreviation for, the American Economic Association, an organization of over 25,000 professional economists. Founded in 1885, this premier top-of-the-economic-association-list publishes the prestigious American Economic Review, arguably THE number one scholarly U.S. economic journal and the Journal of Economic Literature, arguably THE number one index of economic journal publications. The AEA, as acronymically inclined economists call it, also sponsors an annual conference where professional economists present scholarly papers on their latest scholarly research.

AFC: The abbreviation for average fixed cost, which is fixed cost per unit of output, found by dividing total fixed cost by the quantity of output. Average fixed cost is one of three related cost averages. The other two are average variable cost and avarage total cost. Average fixed cost decreases with larger quantities of output. Because fixed cost is FIXED and does not change with the quantity of output, a given cost is spread more thinly per unit as quantity increases. A thousand dollars of fixed cost averages out to $10 per unit if only 100 units are produced. But if 10,000 units are produced, then the average shrinks to a mere 10 cents per unit.

AFL: The abbreviation for the American Federation of Labor, which started as a collection of craft unions in 1886, this is now one half of the umbrella organization for labor unions in the United States (the AFL part of AFL-CIO). As a collection of craft unions, the AFL primarily represented skilled workers in particular occupations. However, it also contained unions representing unskilled industrial workers, which led to a rift among AFL members in 1938 and spawned the formation of the Congress of Industrial Organizations (CIO). This rift was closed in 1955, when both joined together to form the AFL-CIO, which is the primary advocate for workers and labor unions in the United States.

AFL-CIO: The umbrella organization for many labor unions in the United States, with AFL standing for American Federation of Labor, and CIO the abbreviation of Congress of Industrial Organizations. The AFL-CIO began as just the AFL in 1886 as a collection of craft unions representing skilled workers. It expanded to include semiskilled and unskilled workers represented by industrial unions. Differing interests among the two groups lead to a division of the original AFL in 1938 into two separate groups -- the AFL containing craft unions and CIO containing industrial unions. This rift was closed in 1955, when the AFL and CIO merged to form the AFL-CIO.

Agglomeration: The clustering of several similar or related activities at the same location. Many industries have firms that tend to agglomerate, that is, locate very close to one another, leading to geographic concentration. For example, the motion picture industry is concentrated in California, the fashion industry is concentrated in New York, and the petroleum industry is concentrated in Texas. Agglomeration can be caused by accessibility to a concentrated natural resource (such as petroleum or sunny weather), but if often feeds upon itself through agglomeration economies. Firms in the same industry often have lower production cost when the located near their competitors.

Agglomeration Economies: A reduction in production cost the results when related firms locate near one another. Firms can be related as competitors in the same industry, by using the same inputs, or through providing output to the same demographic group. The fashion industry, for example, experiences agglomeration economies because they can share specialized inputs (photographers, models) that would be too expensive to employ full time. Retail stores have agglomeration economies when located in shopping malls because they have access to a large group of potential customers with lower advertising cost. Agglomeration economies is given as one of the primary reasons for the emergence of urban areas.

Aggregate: A common modifier for an assortment of economic terms used in the study of macroeconomics that signifies a comprehensive, often national, total value. This modifier most often surfaces in the study of the AS-AD, or "aggregate market", model of the economy with such terms as aggregate demand and aggregate supply. For example, aggregate demand indicates the total demand for production in the macroeconomy and aggregate supply indicates the total amount of that output produced. Two other noted "aggregate" terms are aggregate expenditures and aggregate production function.

Aggregate Demand: The total (or aggregate) real expenditures on final goods and services produced in the domestic economy that buyers would willing and able to make at different price levels, during a given time period (usually a year). Aggregate demand (AD) is one half of the aggregate market analysis; the other half is aggregate supply. Aggregate demand, relates the economy's price level, measured by the GDP price deflator, and aggregate expenditures on domestic production, measured by real gross domestic product. The aggregate expenditures are consumption, investment, government purchases, and net exports made by the four macroeconomic sectors (household, business, government, and foreign).

Aggregate Demand Curve: A graphical representation of the relation between aggregate expenditures on real production and the price level, holding all ceteris paribus aggregate demand determinants constant. The aggregate demand, or AD, curve is one side of the graphical presentation of the aggregate market. The other side is occupied by the aggregate supply curve (which is actually two curves, the long-run aggregate supply curve and the short-run aggregate supply curve). The negative slope of the aggregate demand curve captures the inverse relation between aggregate expenditures on real production and the price level. This negative slope is attributable to the interest-rate effect, real-balance effect, and net-export effect.

Aggregate Demand Determinant: A ceteris paribus factor that affects aggregate demand, but which is assumed constant when the aggregate demand curve is constructed. Changes in any of the aggregate demand determinants cause the aggregate demand curve to shift. While a wide variety of specific ceteris paribus factors can cause the aggregate demand curve to shift, it's usually most convenient to group them into the four, broad expenditure categories -- consumption, investment, government purchases, and net exports. The reason is that changes in these expenditures are the direct cause of shifts in the aggregate demand curve. If any determinant affects aggregate demand it MUST affect one of these four expenditures.

Aggregate Demand Determinants: An assortment of ceteris paribus factors that affect aggregate demand, but which are assumed constant when the aggregate demand curve is constructed. Changes in any of the aggregate demand determinants cause the aggregate demand curve to shift. While a wide variety of specific ceteris paribus factors can cause the aggregate demand curve to shift, it's usually most convenient to group them into the four, broad expenditure categories -- consumption, investment, government purchases, and net exports. The reason is that changes in these expenditures are the direct cause of shifts in the aggregate demand curve. If any determinant affects aggregate demand it MUST affect one of these four expenditures.

Aggregate Expenditure Determinant: A ceteris paribus factor that affects aggregate expenditures, but which is assumed constant when the aggregate expenditure line is constructed. Changes in any of the aggregate expenditures determinants cause the aggregate expenditure line to shift. While a wide variety of specific ceteris paribus factors can cause the aggregate expenditure line to shift, it's usually most convenient to group them into the four, broad expenditure categories -- consumption, investment, government purchases, and net exports. The reason is that changes in these expenditures are the direct cause of shifts in the aggregate expenditure line. If any determinant affects aggregate expenditures it MUST affect one of these four expenditures.

Aggregate Expenditure Equation: An equation indicating that aggregate expenditures (AE) are the sum of consumption expenditures (C), investment expenditures (I), government purchases (G), and net exports (X-M), stated as: AE = C + I + G + (X-M). This equation surfaces in the Keynesian economic income-expenditure model in the form of the aggregate expenditures line. However, it's also central throughout the study of macroeconomics, including aggregate demand and the measurement of gross domestic product.

Aggregate Expenditure Line: A line representing the relation between aggregate expenditures and gross domestic product used in the Keynesian cross. The aggregate expenditure line is obtained by adding investment expenditures, government purchases, and net exports to the consumption line. As such, the slope of the aggregate expenditure line is largely based on the slope of the consumption line (which is the marginal propensity to consume), with adjustments coming from the marginal propensity to invest, the marginal propensity for government purchases, and the marginal propensity to import. The intersection of the aggregate expenditures line and the 45-degree line identifies the equilibrium level of output in the Keynesian cross.

Aggregate Expenditures: The total expenditures on gross domestic product undertaken in a given time period by the four sectors -- household, business, government, and foreign. Expenditures made by each of these sectors are specifically labeled consumption expenditures, investment expenditures, government purchases, and net exports. Aggregate expenditures (AE) are a cornerstone in the study of macroeconomics, playing critical roles in Keynesian economics, aggregate market analysis, and to a lesser degree, monetarism.

Aggregate Market: An economic model relating the price level and real production that is used to analyze business cycles, gross domestic product, unemployment, inflation, stabilization policies, and related macroeconomic phenomena. The aggregate market, inspired by the standard market model, captures the interaction between aggregate demand (the buyers) and short-run and long-run aggregate supply (the sellers).

Aggregate Market Analysis: An investigation of macroeconomic phenomena, including unemployment, inflation, business cycles, and stabilization policies, using the aggregate market interaction between aggregate demand, short-run aggregate supply, and long-run aggregate supply. Aggregate market analysis, also termed AS-AD analysis, has been the primary method of investigating macroeconomic activity since the 1980s, replacing Keynesian economic analysis that was predominant for several decades. Like most economic analysis, aggregate market analysis employs comparative statics, the technique of comparing the equilibrium after a shock with the equilibrium before a shock. While the aggregate market model is usually presented as a simply graph at the introductory level, more sophisticated and more advanced analyses often involve a system of equations.

Aggregate Market Equilibrium: The state of equilibrium that exists in the aggregate market when real aggregate expenditures are equal to real production with no imbalances to induce changes in the price level or real production. In other words, the opposing forces of aggregate demand (the buyers) and aggregate supply (the sellers) exactly offset each other. The four macroeconomic sector (household, business, government, and foreign) buyers purchase all of the real production that they seek at the existing price level and business-sector producers sell all of the real production that they have at the existing price level. The aggregate market equilibrium actually comes in two forms: (1) long-run equilibrium, in which all three aggregated markets (product, financial, and resource) are in equilibrium and (2) short-run equilibrium, in which the product and financial markets are in equilibrium, but the resource markets are not.

Aggregate Market Shocks: Disruptions of the equilibrium in the aggregate market (or AS-AD model) caused by shifts of the aggregate demand, short-run aggregate supply, or long-run aggregate supply curves. Shocks of the aggregate market are associated with, and thus used to analyze, assorted macroeconomic phenomena such as business cycles, unemployment, inflation, stabilization policies, and economic growth. The specific analysis of aggregate market shocks identifies changes in the price level (GDP price deflator) and real production (real GDP). However, changes in the price level and real production have direct implications for the unemployment rate, the inflation rate, national income, and a host of other macroeconomic measures.

Aggregate Output: The macroeconomy's total production of final goods and services. You might recognized it by it's official term gross domestic product. Another related term is aggregate supply. This is the total production in the economy that is purchased by the four basic economic sectors -- household, business, government, and foreign. See also aggregate market, aggregate demand, aggregate expenditures.

Aggregate Production Function: A relation between the total production of real output for an economy and the amount of labor input. The aggregate production function is comparable to the standard production function used in the microeconomic analysis of firm behavior but is applied to the macroeconomic study of aggregate supply, resource markets, and employment. It is typically assumed to experience diminishing marginal returns, resulting in a decreasing marginal product of labor.

Aggregate Supply: The total (or aggregate) real production of final goods and services available in the domestic economy at a range of price levels, during a given time period. Aggregate supply (AS) is one half of the aggregate market analysis; the other half is aggregate demand. Aggregate supply, relates the economy's price level, measured by the GDP price deflator, and aggregate domestic production, measured by real gross domestic product. The aggregate supply relation is generally separated into long-run aggregate supply, in which all prices and wages and flexible and all markets are in equilibrium, and short-run aggregate supply, in which some prices and wage are NOT flexible and some markets are NOT in equilibrium.

Aggregate Supply Curve: A graphical representation of the relation between real production and the price level, holding all ceteris paribus aggregate supply determinants constant. There are actually two separate aggregate supply curves, one for the long run and one for the short run. These aggregate supply curves are one side of the graphical presentation of the aggregate market. The other side is occupied by the aggregate demand curve.

Aggregate Supply Determinants: An assortment of ceteris paribus factors that affect both short-run aggregate supply and long-run aggregate supply, but which are assumed constant when the short-run and long-run aggregate supply curves are constructed. Changes in any of the aggregate supply determinants cause the short-run and long-run aggregate supply curves to shift. While a wide variety of specific ceteris paribus factors can cause the aggregate supply curves to shift, it's usually most convenient to group them into three broad categories -- resource quantity, resource quality, and resource prices.

Aggregate Supply Shifts: Changes in the aggregate supply determinants can shift either the short-run aggregate supply curve and the long-run aggregate supply curve. The mechanism is comparable to that for market supply determinants and market supply. We have two options -- an increase in aggregate supply and a decrease in aggregate supply. An increase in resource quantity or quality or a decrease in resource prices shift the aggregate supply curves to right. A decrease in resource quantity or quality or an increase in resource prices shift the aggregate supply curves to left.

Aggregation: The process of adding up, summing, or otherwise identifying the total value of a variable or measure, especially when used in the study of macroeconomics. Common items that are aggregated are demand, supply, and expenditures on gross domestic product, which result in aggregate demand, aggregate supply, and aggregate expenditures.

Agrarian: A term signifying a connection to farming, agricultural production, or the land. Agrarian is often used as a modifier for other terms, such as agrarian society (an economy that relies heavily on agricultural production), agrarian society (a society based on the institutions that emerge from a heavy reliance on agricultural production), or agrarian movement (a political movement designed to product agricultural production). Because farming was one of the first and remains one of the most fundamental activities undertaken by even the most primitive society, agrarian is typically associated with less developed, as in the phrase a "less developed, agrarian nation."

Allocation: The process of distributing resources for the production of goods and services, and of distributing goods and services for consumption by households. This process of allocation is essential to an economy's effort to address the problem of scarcity. An allocation is efficient if the resources, goods, and services are distributed according to the economy's highest valued uses.

Allocative Efficiency: Obtaining the most consumer satisfaction from available resources. Allocative efficiency means that our economy is doing the best job possible of satisfying unlimited wants and needs with limited resources -- that is, of addressing the problem of scarcity.

Alternative Unemplyment Rates: The official unemployment rate estimated and reported monthly by the Bureau of Labor Statistics (BLS) using data from Current Population Survey is one of six alternative measures of unemployment tracked by the BLS, officially labeled U1-U6. The "official" unemployment rate is U3. The other five measures seek to document different ways in which labor can be underutilized, including unemployment duration, job losers, discouraged workers, marginally-attached workers, and part-time workers.

American Economic Association: An organization of over 25,000 professional economists. Founded in 1885, this premier top-of-the-economic-association-list publishes the prestigious American Economic Review, arguably THE number one scholarly U.S. economic journal and the Journal of Economic Literature, arguably THE number one index of economic journal publications. The AEA, as acronymically inclined economists call it, also sponsors an annual conference where professional economists present scholarly papers on their latest scholarly research.

American Federation of Labor: Started as a collection of craft unions in 1886, this is now one half of the umbrella organization for labor unions in the United States (the AFL part of AFL-CIO). As a collection of craft unions, the AFL primarily represented skilled workers in particular occupations. However, it also contained unions representing unskilled industrial workers, which led to a rift among AFL members in 1938 and spawned the formation of the Congress of Industrial Organizations (CIO). This rift was closed in 1955, when both joined together to form the AFL-CIO, which is the primary advocate for workers and labor unions in the United States.

American Stock Exchange: One of three national stock markets in the United States (see National Association of Securities Dealers and New York Stock Exchange) that trade ownership shares in corporations. In terms of daily stock transactions and the number of stocks listed, the American Stock Exchange is the smallest of these three. However, it's composite index of stock prices -- AMEX is considered important enough to be flashed briefly on the nightly news.

AMEX: The common abbreviation for the American Stock Exchange, which is one of three national stock markets in the United States (see National Association of Securities Dealers and New York Stock Exchange) that trade ownership shares in corporations. In terms of daily stock transactions and the number of stocks listed, the American Stock Exchange is the smallest of these three. However, it's composite index of stock prices -- AMEX is considered important enough to be flashed briefly on the nightly news.

Amortization: The process of paying off a debt liability and accrued interest through a series of equal, periodic payments. Car loans and mortgages are two debts commonly paid off through amortization. Your monthly car payment, for example, partially pays for interest accrued on the outstanding balance and partly reduces that balance. Because one payment reduces the outstanding balance, each subsequent payment has a smaller portion for interest. If the proper amortization schedule has been calculated, your loan will be paid off with the last payment.

Annual: A standard 12-month period, or one year, used for reporting economic and financial data. Gross Domestic Product and related measures are noted economic data released annually. Many businesses also provide annual financial reports. Another standard reporting period is the quarter.

Annuity: The receipt of payments at regular intervals from a established fund. Annuities are commonly used for insurance and retirement programs. It works in this way: A fund, which can be established either through a one-time sum of money or a series of payments, is exhausted over time with fixed, periodic payments. The amount of each payment depends on the interest accrued on the outstanding balance in the fund, and the length of time scheduled to exhaust the fund. For example, if your pension plan is based on an annuity that begins payments at the age of 65, then the size of the payments depends on whether you expect to live 5, 10, 15, or more years and set up payments accordingly. It's very similar to amortization, but in the reverse direction.

Antitrust: The generally process of preventing monopoly practices or breaking up monopolies that restrict competition. The term antitrust derives from the common use of the trust organizational structure in the late 1800s and early 1900s to monopolize markets. The most noted example of the use of a monopoly trust was the Standard Oil Trust, controlled by J. D. Rockefeller and dismantled through the Sherman Act in 1911. The creation of similar monopoly trusts led to the several antitrust laws, including the Sherman Act, the Clayton Act, and the Federal Trade Commission Act.

Antitrust Laws: A series of laws passed by the U. S. government that tries to maintain competition and prevent businesses from getting a monopoly or otherwise obtaining and exerting market control. The first of these, the Sherman Antitrust Act, was passed in 1890. Two others, the Clayton Act and the Federal Trade Commission Act, were enacted in 1914. These laws impose all sorts of restrictions on business ownership, control, mergers, pricing, and how businesses go about competing (or cooperating) with each other.

AP: The abbreviation for average product, which is the quantity of total output produced per unit of a variable input, holding all other inputs fixed. It is found by dividing total product by the quantity of the variable input. Average product, abbreviated AP also goes by the alias of average physical product (APP), so don't be confused by the extra term (physical).

APC: The abbreviation for average propensity to consume, which is the proportion of income, usually measured as disposable income or national income, used for household consumption expenditures. It is found by dividing consumption by income. The average propensity to consume, abbreviated APC, most often pops up in discussions of Keynesian economics. The average propensity to consume is the average amount of total household income that is devoted consumption expenditures.

APP: The abbreviation of average physical product, which is the quantity of total output produced per unit of a variable input, holding all other inputs fixed. Average physical product, usually abbreviated APP, is found by dividing total physical product by the quantity of the variable input. Average physical product is actually just another name for average product (AP). But don't be confused by the extra term (physical).

Appreciation: A more or less permanent increase in value or price. "More or less permanent" doesn't include temporary, short-term jumps in price that are common in many markets. Appreciation is only those price increases that reflect greater consumer satisfaction and thus value. While all sorts of stuff can appreciate in value, some of the more common ones are real estate, works of art, corporate stock, and money. In particular, the appreciation of a nation's money is seen by an increase in the exchange rate caused by a growing, expanding, and healthy economy.

AR: The abbreviation for average revenue, which is the revenue received for selling a good, per unit of output sold, found by dividing total revenue by the quantity of output. Average revenue actually goes by a simpler and more widely used term... price. Average revenue is really a fancy-schmancy term for the price received by a seller for selling a good. However, using the longer term average revenue let's us see the connection with other terms, like total revenue, marginal revenue, and quantity.

ARP: The abbreviation for average revenue product, which is total revenue generated per unit of a variable input, keeping all other inputs unchanged. Average revenue product, usually abbreviated ARP, is found by dividing total revenue by the variable input. Average revenue product is most often used in the analysis of the demand for productive inputs.

Arbitrage: Buying something in one market then immediately (or as soon as possible) selling it in another market for (hopefully) a higher price. Arbitrage is a common practice in financial markets. For example, an aspiring financial tycoon might buy a million dollars worth of Japanese yen in the Tokyo foreign exchange market then resell it immediately in the New York foreign exchange market for more than a million dollars. Arbitrage of this sort does two things. First, it often makes arbitragers wealthy. Second, it reduces or eliminates price differences that exist between two markets for the same good.

Arbitration: Intervention of an impartial third party to settle disputes between two others. The decisions of this third party -- the arbitrator -- are legally binding, much like the ruling of a judge in a court of law. Arbitration is commonly used to interpret a collective bargaining agreement between unions and employers. Much like a judge (in some cases it is a judge) an arbitrator determines how a given union and employer conflict stacks up against the terms of existing agreement. Note that an arbitrator doesn't try to decide what's "best, "fair," or mutually agreeable to both sides -- as would be the case with mediation -- but only what's in line with the existing agreement.

Arc Elasticity: The average elasticity for discrete changes in two variables, A and B. The distinguishing characteristic of arc elasticity is that percentage changes are calculated based on the average of the initial and ending values of each variable, rather than only initial values. Arc elasticity is generally calculated using the midpoint formula. Arc elasticity should be compared with point elasticity. For infinitesimally small changes in variables A and B, arc elasticity is the same as point elasticity.

AS: The abbreviation for aggregate supply, which is the total (or aggregate) real production of final goods and services available in the domestic economy at a range of price levels, during a given time period. Aggregate supply (AS) is one half of the aggregate market analysis; the other half is aggregate demand. Aggregate supply, relates the economy's price level, measured by the GDP price deflator, and aggregate domestic production, measured by real gross domestic product. The aggregate supply relation is generally separated into long-run aggregate supply, in which all prices and wages and flexible and all markets are in equilibrium, and short-run aggregate supply, in which some prices and wage are NOT flexible and some markets are NOT in equilibrium.

AS-AD Analysis: An economic model relating the price level and real production that is used to analyze business cycles, gross domestic product, unemployment, inflation, stabilization policies, and related macroeconomic phenomena. The AS-AD model, inspired by the standard market model, captures the interaction between aggregate demand (the buyers) and short-run and long-run aggregate supply (the sellers).

AS-AD Model: An economic model relating the price level and real production that is used to analyze business cycles, gross domestic product, unemployment, inflation, stabilization policies, and related macroeconomic phenomena. The AS-AD model, inspired by the standard market model, captures the interaction between aggregate demand (the buyers) and short-run and long-run aggregate supply (the sellers).

Asset: Something that you own. For a person, assets can be financial, like money, stocks, bonds, bank accounts, and government securities, or they can be physical things, like cars, boats, houses, clothes, food, and land. The important assets for our economy are the output we have produced and the resources, capital, and natural resources used to produce that output.

Assumption: An initial condition or statement that sets the stage for an analysis by abstracting from the real world. Assumptions are important to economic theories and economic analysis. Some assumptions are used to simplify a complex analysis into more easily manageable parts. These establish idealistic benchmarks that can be used to evaluate real world conditions. Other assumptions are used as control conditions that are subsequently changed to evaluate the effect of the change. The use of ceteris paribus assumptions in comparative statics analysis is an excellent example.

Assumptions, Production Possibilities: Production possibilities analysis is based on four key assumptions: (1) resources are used to produce one or both of only two goods, (2) the quantities of the resources do not change, (3) technology and production techniques do not change, and (4) resources are used in a technically efficient way.

Asymetric Information: The economics of information search tells us that everyone falls short of having perfect information. It suggests that everyone will have different information about different things. For example, if you aren't a plumber (nor have any desire to become one), then you aren't likely to seek information about the wages paid plumbers in Boise, Idaho. In contrast, this information could be quite beneficial to plumbers in Pocatello, Idaho.

ATC: The abbreviation for average total cost, which is total cost per unit of output, found by dividing total cost by the quantity of output. Average total cost can be found in two ways. Because average total cost is total cost per unit of output, it can be found by dividing total cost by the quantity of output. Alternatively, because total cost is the sum of total variable cost and total fixed cost, average total cost can be derived by summing average variable cost and average fixed cost.

Attractive Force: A force that causes activities to locate closer together. One primary attractive force is transportation cost and the weight of an activity. In this case, activities locate close together to reduce transportation cost. Another is agglomeration and urban economies. In this case, activities locate close together to lower other production cost. Attractive forces are countered by dispersive forces, which act to force activities farther apart.

Auctions: Formal markets where buyers and sellers come together to negotiate a price. Auctions are commonly held for agricultural commodities, financial instruments, and works of art. The four most common types of auctions are English, Dutch, sealed-bid, and Walrasian tatonnement.

Automatic Stabilizer: A feature of the federal government's budget that tends to reduce the ups and downs of the business cycle without the need for any special legislative action, that is stabilization policies. The two key automatic stabilizers are income taxes and transfer payments. When our economy drops into a recession, unemployment rises, aggregate output declines, and people have less income. But with less income, they pay fewer income taxes, and thus there's less of a drain on consumption than their might have been. Likewise, many who are unemployed get transfer payments in the form of unemployment compensation, welfare, or Social Security. This lets them consume more than they would have otherwise. During an expansion, both of these go in the other direction. As a result, a recession sees more spending and fewer taxes, while an expansion has less spending and more taxes, all occurring quite automatically.

Autonomous: The general notion that changes in one variable are NOT related to, or caused by, changes in another variable. Autonomous relations, especially changes in aggregate expenditures that disrupt the macroeconomy, are a key aspect of Keynesian economics and business cycles The alternative to an autonomous relation between variables is an induced relation, in which one variable is related to another.

Autonomous Change: A change in autonomous expenditures that sets in motion a change in the national income and gross domestic product through the multipiler. In terms of Keynesian economics and the Keynesian cross diagram, autonomous changes are seen as shifts in the aggregate expenditures line. Autonomous changes cause changes in income and production which then "induce" further changes in aggregate expenditures, especially consumption expenditures, which are induced changes. This two step process, autonomous changes causing induced changes, is key to explaining business cycle fluctuations.

Autonomous Consumption: Household consumption expenditures that are unrelated to income or production (especially disposable, national income, or gross national product). These are consumption expenditures that would occur even if household disposable income was zero. Autonomous consumption is graphically depicted as the vertical intercept of the consumption or propensity-to-consume line. Autonomous saving is the equal to the negative value of autonomous consumption. Changes in autonomous consumption, along with changes in other autonomous expenditures, are what trigger the multiplier effect.

Autonomous Expenditure: An aggregate expenditure (you know them as consumption, investment, government purchases, and net exports) that is unrelated to national income or gross domestic product. These four aggregate expenditures are conveniently separated into two types, autonomous, which is our current topic of expenditures unrelated to national income or GDP, and induced expenditures, expenditures which ARE related to national income or GDP. Autonomous expenditures cause shocks in the macroeconomy, which result in changes in income and production. These income/production changes then "induce" further changes in aggregate expenditures, our induced expenditures.

Autonomous Government Purchases: Government purchases that are unrelated to income or production (especially national income or gross national product). These are government purchases that would occur even if national income was zero. Autonomous government purchases are graphically depicted as the vertical intercept of the government purchases line relating government purchases to national income. Changes in autonomous government purchases, along with changes in other autonomous expenditures, are what trigger the multiplier effect.

Autonomous Investment: Business investment expenditures that are unrelated to income or production (especially national income or gross national product). These are investment expenditures that would occur even if national income was zero. Autonomous investment is graphically depicted as the vertical intercept of the investment line relating investment to national income. Changes in autonomous investment, along with changes in other autonomous expenditures, are what trigger the multiplier effect.

Autonomous Saving: Household saving that is unrelated to income or production (especially disposable, national income, or gross national product). This is saving that would occur even if household disposable income was zero. Autonomous saving is graphically depicted as the vertical intercept of the saving or propensity-to-save line. Autonomous saving is the equal to the negative value of autonomous consumption. Changes in autonomous saving, along with changes in autonomous expenditures, are what trigger the multiplier effect.

Average Cost: The opportunity cost incurred per unit in the production of a good. This can be calculated by dividing the total cost of production by the quantity of output produced. While average cost is a general term relating cost and the quantity of output, three more specific average cost terms that are worth a closer look are average total cost, average variable cost, and average fixed cost. As long as you're looking into cost, you might want to spend a little time with the most important member of the cost family of terms, marginal cost.

Average-Cost Pricing: A regulatory policy used for public utilities (especially those that are natural monopolies) in which the price received by a firm is set equal to the average total cost of production. The great thing about average-cost pricing is that a regulated public utility is guaranteed a normal profit, usually termed a fair rate of return. One bad thing about average-cost pricing is that marginal cost is less than average total cost meaning that price is greater than marginal cost. As such, the public utility is NOT operating according to the price equals marginal cost (P = MC) rule of efficiency.

Average Factor Cost: Total factor cost per unit of factor input, found by dividing total factor cost by the quantity of factor input. Average factor cost, abbreviated AFC, is essentially the factor price. However, using the longer term average factor cost let's us see the connection with other terms, like total factor cost and marginal factor cost.

Average Factor Cost Curve: A curve that graphically represents the relation between average factor cost incurred by a firm for buying or hiring a factor of production and the factor quantity. Because average factor cost is essentially factor price, the average factor cost curve (in most circumstances) is also the factor supply curve facing the firm. This curve is constructed to capture the relation between average factor cost and the factor quantity, holding other variables constant.

Average Fixed Cost: Fixed cost per unit of output, found by dividing total fixed cost by the quantity of output. Average fixed cost is one of three related cost averages. The other two are average variable cost and average total cost. Average fixed cost, usually abbreviated AFC, decreases with larger quantities of output. The logic behind this relationship is relatively simply. Because fixed cost is FIXED and does not change with the quantity of output, a given cost is spread more thinly per unit as quantity increases. A thousand dollars of fixed cost averages out to $10 per unit if only 100 units are produced. But if 10,000 units are produced, then the average shrinks to a mere 10 cents per unit.

Average Fixed Cost Curve: A curve that graphically represents the relation between average fixed cost incurred by a firm in the short-run product of a good or service and the quantity produced. This curve is constructed to capture the relation between average fixed cost and the level of output, holding other variables, like technology and resource prices, constant. The average fixed cost curve is one the three average curves. The other two are average total cost curve and average variable cost curve.

Average-Marginal Rule: An intriguing, extremely useful mathematical relationship between an average measure and it's corresponding marginal measure, for example average product and marginal product, or average total cost and marginal cost. When the marginal measure is greater than the average measure, then the average measure increases. Alternatively, when the marginal measure is less than the average measure, then the average measure decreases. In addition, when the marginal measure is equal to the average measure the average measure doesn't change.

Average Physical Product: The quantity of total output produced per unit of a variable input, holding all other inputs fixed. Average physical product, usually abbreviated APP, is found by dividing total physical product by the quantity of the variable input. Average physical product is actually just another name for average product (AP). But don't be confused by the extra term (physical).

Average Product: The quantity of total output produced per unit of a variable input, holding all other inputs fixed. It is found by dividing total product by the quantity of the variable input. Average product, abbreviated AP also goes by the alias of average physical product (APP), so don't be confused by the extra term (physical). Compare this term with marginal product and average revenue product when you have a chance. If you haven't yet come across the term, then you really should spend some time with the law of diminishing marginal returns. The average-marginal rule is also worth a look.

Average Product Curve: A curve that graphically illustrates the relation between average product and the quantity of the variable input, holding all other inputs fixed. This curve indicates the per unit output at each level of the variable input. The average product curve is one of three related curves used in the analysis of the short-run production of a firm. The other two are total product curve and marginal product curve. To be quite honest, the average product curve is the least important of the three for economic analysis. Economists are generally more interested in totals and marginals than averages.

Average Product And Marginal Product: A mathematical connection between marginal product and average product stating that the change in the average product depends on a comparison between the average product and marginal product. If marginal product is less than average product, then average product declines. If marginal product is greater than average product, then average product rises. If marginal product is equal to average product, then average product does not change.

Average Propensity To Consume: The proportion of income, usually measured as disposable income or national income, used for household consumption expenditures. It is found by dividing consumption by income. The average propensity to consume, abbreviated APC, most often pops up in discussions of Keynesian economics. The average propensity to consume is the average amount of total household income that is devoted consumption expenditures. For closely related information see marginal propensity to consume, average propensity to save, marginal propensity to save, and consumption function.

Average Propensity To Save: The proportion of income, usually measured as disposal income or national income, used for household saving. It is found by dividing saving by income. The average propensity to save, abbreviated APS, is most relevant for discussions of Keynesian economics. The average propensity to save is the average amount of total household income that is devoted to saving and NOT used for consumption expenditures.

Average Revenue: The revenue received for selling a good, per unit of output sold, found by dividing total revenue by the quantity of output. Average revenue, abbreviated AR, actually goes by a simpler and more widely used term... price. Average revenue is really a fancy-schmancy term for the price received by a seller for selling a good. However, using the longer term average revenue let's us see the connection with other terms, like total revenue, marginal revenue, and quantity.

Average Revenue Curve: A curve that graphically represents the relation between average revenue received by a firm for selling its output and the quantity of output sold. Because average revenue is essentially the price of a good, the average revenue curve (in most circumstances) is also the demand curve for a firm's output. This curve is constructed to capture the relation between average revenue and the level of output, holding other variables constant.

Average Revenue Curve, Monopolistic Competition: A curve that graphically represents the relation between average revenue received by a monopolistically competitive firm for selling its output and the quantity of output sold. Because average revenue is essentially the price of a good, the average revenue curve is the demand curve for the firm's output. In general, the average revenue curve reflects the degree of market control held by a firm. For a monopolistically competitive firm with a small degree of market control, the average revenue (and demand) curve is negatively-sloped. The average revenue is used in conjunction with a firm's average total cost curve to determine economic profit.

Average Revenue Curve, Monopoly: A curve that graphically represents the relation between average revenue received by a monopoly firm for selling its output and the quantity of output sold. Because average revenue is essentially the price of a good, the average revenue curve (in most circumstances) is also the demand curve for a monopoly firm's output. The negative slope of the average revenue curve indicates that a monopoly has market control. The average revenue is used in conjunction with the monopoly's average total cost curve to determine economic profit.

Average Revenue, Monopoly: The per unit revenue received by a monopoly firm for selling its output. It is found by dividing total revenue by the quantity of output. Average revenue is also the price received by a monopoly for selling its output. Because average revenue is price and because the demand for a monopoly's output is the market demand for the good, the average revenue received by a monopoly depends on the quantity sold. A monopoly firm sees average revenue decrease as the quantity of output sold increases. For relatively small quantities, average revenue is relatively high. For relatively larger quantities, average revenue is less.

Average Revenue, Monopolistic Competition: The revenue a monopolistically competitive firm receives for selling a good per unit of output sold, found by dividing total revenue by the quantity of output. Average revenue is a polysyllabic term for the price a monopolistically competitive firm receives for selling its' good. For a firm operating under monopolistic competition, average revenue decreases as the quantity of output increases. The decreasing nature of average revenue is a prime indication of the market control of a firm.

Average Revenue Product: Total revenue generated per unit of a variable input, keeping all other inputs unchanged. Average revenue product, usually abbreviated ARP, is found by dividing total revenue by the variable input. Average revenue product is most often used in the analysis of the demand for productive inputs.

Average Total Cost: Total cost per unit of output, found by dividing total cost by the quantity of output. Average total cost, usually abbreviated ATC, can be found in two ways. Because average total cost is total cost per unit of output, it can be found by dividing total cost by the quantity of output. Alternatively, because total cost is the sum of total variable cost and total fixed cost, average total cost can be derived by summing average variable cost and average fixed cost.

Average Total Cost Curve: A curve that graphically represents the relation between average total cost incurred by a firm in the short-run product of a good or service and the quantity produced. The average total cost curve is constructed to capture the relation between average total cost and the level of output, holding other variables, like technology and resource prices, constant. The average total cost curve is one the three average curves. The other two are average variable cost curve and average fixed cost curve.

Average Variable Cost: Total variable cost per unit of output, found by dividing total variable cost by the quantity of output. Average variable cost, abbreviated AVC, decreases with additional production at relatively small quantities of output, then eventually increases with relatively larger quantities of output. This pattern is illustrated by a U-shaped average variable cost curve. The logic behind this decrease-increase U-shaped pattern can be found with a closer examination of the law of diminishing marginal returns, average product, and the average-marginal rule. You should also check out marginal cost.

Average Variable Cost Curve: A curve that graphically represents the relation between average variable cost incurred by a firm in the short-run production of a good or service and the quantity produced. This curve is constructed to capture the relation between average variable cost and the level of output, holding other variables, like technology and resource prices, constant. The average variable cost curve is one the three average curves. The other two are average total cost curve and average fixed cost curve.

Axes: Two number lines that are joined at a right angle such that they intersect at their zero points (called the origin). The vertical axis is by convention termed the Y-axes and the horizontal axis is termed the X-axis. These axes are used to locate or plot pairs of numbers in coordinate space, one value for the X-variable coordinate and a corresponding value for the Y-variable coordinate. More often than not, coordinate number pairs are used to plot relationships that can be connected by one or more lines. This line construction procedure is one of the more powerful tools used by economists. Economists typically analyze relationships between two variables, such as price and quantity demanded. By letting one axis measure price and the other measure quantity demanded, these axes form the framework, the guidelines if you will, for constructing a demand curve (the relationship between price and quantity demanded). Once we have an abstract relationship graphed out, then it can be used to perform all sorts of economic analysis.

Axiom: A basic precondition or assumption underlying a theory. Axioms are basic, unverifiable world view assumptions, including personal beliefs, political views, and cultural values, that form the foundation of a theory. These axioms can not be verified with real world data, and as such are largely accepted on faith. Belief in a supreme, omnipotent, omniscience being is one such axiom. The notion that people are basically good (or bad) is another. The presumption that the universe abides by cause-and-effect relationships is a key axiom for science.