Microeconomics Chapter 2A

pie chart

a circular graph that shows how some total is divided among its components, usually expressed in percentages.

nonlinear curve

a curve in which the slope is not the same between every pair of points.

scatter diagram

a graph that shows points that correspond to actual observations of the x- and y-variables; a curve is usually fitted to the scatter of points to indicate the trend in the data

bar graph

a graph that uses bars of varying heights or lengths to show the comparative sizes of different observations of a variable.

curve

a line on a graph, which may be curved or straight, that depicts a relationship between two variables.

slope

a measure of how steep a line or curve is. The slope of a line is measured by "rise over run"--the change in the y-variable between two points on the line divided by the change in the x-variable between those same two points.

variable

a quantity that can take on more than one value.

negative relationship

a relationship between two variables in which an increase in the value of one variable is associated with a decrease in the value of the other variable. It is illustrated by a curve that slopes downward from left to right.

positive relationship

a relationship between two variables in which an increase in the value of one variable is associated with an increase in the value of the other variable. It is illustrated by a curve that slopes upward from left to right.

tangent line

a straight line that just touches a nonlinear curve at a particular point; the slope of the tangent line is equal to the slope of the nonlinear curve at that point.

time-series graph

a two-variable graph that has dates on the horizontal axis and values of a variable that occurred on those dates on the vertical axis.

omitted variable

an unobserved variable that, through its influence on other variables, creates the erroneous appearance of a direct causal relationship among those variables.

truncated

cut; in a truncated axis, some of the range of values are omitted, usually to save space.

dependent variable

the determining variable in a causal relationship.

independent variable

the determining variable in a causal relationship.

reverse causality

the error committed when the true direction of causality between two variables is reversed, and the independent variable and the dependent variable are incorrectly identified.

maximum

the highest point on a nonlinear curve, where the slope changes from positive to negative.

x-axis

the horizontal number line of a graph along which values of the x-variable are measured; also referred to as the horizontal axis.

horizontal axis

the horizontal number line of a graph along which values of the x-variable are measured; also referred to as the x-axis.

minimum

the lowest point on a nonlinear curve, where the slope changes from negative to positive.

horizontal intercept

the point at which a curve hits the horizontal axis; it indicates the value of the x-variable when the value of the y-variable is zero.

vertical intercept

the point at which a curve hits the vertical axis; it shows the value of the y-variable when the value of the x-variable is zero.

linear relationship

the relationship between two variables in which the slope is constant and therefore is depicted on a graph by a curve that is a straight line.

nonlinear relationship

the relationship between two variables in which the slope is not constant and therefore is depicted on a graph by a curve that is not a straight line.

causal relationship

the relationship between two variables in which the value taken by one variable directly influences or determines the value taken by the other variable.

absolute value

the value of a number without regard to a plus or minus sign.

y-axis

the vertical number line of a graph along which values of the y-variable are measured; also referred to as the vertical axis.

vertical axis

the vertical number line of a graph along which values of the y-variable are measured; also referred to as the y-axis.