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Definition
| a quantity that can take on more than one value |
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| exists between two variables when the value taken by one variable directly influences or determines the value taken by the other variable. |
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| if the curve is a straight line, the variables have a linear relationship |
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| if the curve is not a straight line, the variables have a nonlinear relationship |
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| 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 |
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| 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. |
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| 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 |
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| 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 |
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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
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| is one in which the slope is not the same between every pair of points |
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| the value of a negative number without the minus sign |
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| 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 |
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| 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. |
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| 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. |
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Definition
| has dates on the horizontal axis and values of a variable that occured on those dates on the vertical axis |
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| shows points that correspond to actual observations of the x- and y-variables. A cure is usually fitted to the scatter of points |
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| shows how some total is diided among its components, usually expressed in percentages |
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| uses bars of varying height or length to show the comparative sizes of different observations of a variable |
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| an axis is truncated when some of the values on the axis are omitted, usually to save space |
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Definition
| an unobserved variable that, through its influence on other variables, creates the erroneous appearance of a direct causal relationship among those variables |
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Definition
| an error committed when the true direction of causality between two variables is reversed |
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