4.1-4.4 Statistics vocab

response variable

the variable whose value can be explained by the value of the explanatory or predictor variable

explanatory varible

explain variability in the response variable

scatter diagram

a graph that shows the relationship between two quantitative variables measured on the same individua

positively associated

above-average values of one variable are associated with above-average values of the other variable and below-average values of one variable are associated with below-average values of the other variable

negatively associated

above-average values of one variable are associated with below-average values of the other variable

linear correlation coefficient

measure of the strength and direction of the linear relation between two quantitative variables

Confounding

any relation that may exist between two variables may be due to a third variable not accounted for in the study

good fit

the line drawn appears to describe the relation between the two variables well.

residual

how close our prediction comes to the actual observation

Least-squares Regression Criterion

the line that minimizes the sum of the squared errors

coefficient of determination, R2

measures the proportion of total variation in the response variable that is explained by the least-squares regression line, closer to 1 or -1 the better, closer to zero the worse

influential observation

observation that significantly affects the least-squares regression line’s slope and/or y-intercept, or the value of the correlation coefficient

marginal distribution

a frequency or relative frequency distribution of either the row or column variable in the contingency table

simpson’s paradox

an association between two variables inverts or goes away when a third variable is introduced to the analysis