# Shared Flashcard Set

## Details

Intro to Macro; Chapter 2 App.
Graphs in economics
21
Economics
02/02/2008

Term
 variable
Definition
 a quantity that can take on more than one value
Term
 causal relationship
Definition
 exists between two variables when the value taken by one variable directly influences or determines the value taken by the other variable.
Term
 linear relationship
Definition
 if the curve is a straight line, the variables have a linear relationship
Term
 nonlinear relationship
Definition
 if the curve is not a straight line, the variables have a nonlinear relationship
Term
 positive relationship
Definition
 when an increase in the value of one variable is associated with an increase in the value of the other variable.  It's illustrated by a cure that slopes upward from left to right
Term
 negative relationship
Definition
 when an increase in the alue of one variable is associated with a decrease in the value of the other variable.  It's illustrated by a curve that slopes downward from left to right.
Term
 horizontal intercept
Definition
 the horizontal intercept of a curve is the point at which it hits the horizontal axis; it indicates the value of the x-variable when the alue of the y-variable is zero
Term
 vertical intercept
Definition
 the point at which the curve hits the vertical axis; it shows the value of the y-variable when the value of the x-variable is zero
Term
 slope
Definition
 the slope of a line or curve is a measure of how steep it 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
Term
 nonlinear curve
Definition
 is one in which the slope is not the same between every pair of points
Term
 absolute value
Definition
 the value of a negative number without the minus sign
Term
 tangent line
Definition
 a straight line that just touches, or is tangent to, 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
Term
 maximum
Definition
 a nonlinear curve may have a maximum point, the highest point along the curve.  At the maximum, the slope of the curve changes from positive to negative.
Term
 minimum
Definition
 a nonlinear curve may have a minimum point, the lowest point along the curve.  At the minimum, the slope of the curve changes from negative to positive.
Term
 time-series graph
Definition
 has dates on the horizontal axis and values of a variable that occured on those dates on the vertical axis
Term
 scatter diagram
Definition
 shows points that correspond to actual observations of the x- and y-variables.  A cure is usually fitted to the scatter of points
Term
 pie chart
Definition
 shows how some total is diided among its components, usually expressed in percentages
Term
 bar graph
Definition
 uses bars of varying height or length to show the comparative sizes of different observations of a variable
Term
 truncated
Definition
 an axis is truncated when some of the values on the axis are omitted, usually to save space
Term
 omitted variable
Definition
 an unobserved variable that, through its influence on other variables, creates the erroneous appearance of a direct causal relationship among those variables
Term
 reverse causality
Definition
 an error committed when the true direction of causality between two variables is reversed
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