measure the direction and strength of the linear relationship between two quantitative variables.
scatterplot of the residuals against the explanatory variable. help asses how well a regression line fits the data.
difference between an observed data value of the response variable and the value predicted by the regression line.
use of a regression line for prediction far outside the interval of values of the explanatory variable x used to obtain the line.
line that describes how a response variable y changes as an explanatory x changes. we use it to predict the value of y for a given value of x.
when above average values of one tend to accompany below average values of the other.
above average values of one tend to accompany above average values of the other, and when below values tend to occur together.
shows the relationship between two quantitative variables measured on the same individuals. data appears as a point on the graph.
observes individuals and measures variables of interest but does not attempt to influence the responses.
data that were produced in the past for some other purpose but that may help answer a present question.