Bvd Chapter3

measure the direction and strength of the linear relationship between two quantitative variables.
residual plot
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.
regression 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.
negative association
when above average values of one tend to accompany below average values of the other.
positive association
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.
explanatory variable
may help explain or influence changes in a response variable.
response variable
measure an outcome of a study.
specific experimental condition applied to the units.
deliberately imposes some treatment on individuals in order to observe their responses.
observational study
observes individuals and measures variables of interest but does not attempt to influence the responses.
available data
data that were produced in the past for some other purpose but that may help answer a present question.
arrangements or patterns for producing data.