AP Stat Unit 3

what is the respone variable?

measures the outcome

what is the explanatory variable?

attempts to predict/explain the response variable

which axis is the response variable on?

y-axis

what axis is the explanatory variable on?

x-axis

how are scatterpolts labeled?

y (response) vs. x (explanatory)

scatterpolts graph…

association, not cause and effect

what is a lurking variable?

variable that is not recorded in a study but has an effect on the relationship between x and y

how to describe scatterpolts:

1. direction (positive, negative, none)

2. unusual features (gaps, outliers, etc.)

3. form (linear, nonlinear)

4. strength (weak, moderate, strong)

what is correlation (r)?

statistic that measures stength and direction of a linear relationship between two quantitative variables

how to find correlation on calculator?

fill L1 and L2 → stat → CALC → LinReg (a + bx)

the closer r is ± 1…

the stronger the linear relationship

is r resistant?

no (found using mean and s)

does r for (x, y) = r for (y, x)?

yes (z_xz_y = z_yz_x)