Scatterplots and Correlation

Response Variable

measures a outcome of a study

Explanatory Variable

may help predict or explain changes in a response variable

Scatterplot

shows the relationship between two quantitative variables measured on the same individuals. The values of one variable appear on the horizontal axis and the values of the other variable appear on he vertical axis. Each individual in the data set appears as a point in the graph.

Positive Association

when values of one variable tend to increase as the values of the other variable increase

Negative Association

when values of one variable tend to decrease as the values of the other variable increases

No Association

between two variables if knowing the value of one variable does not help predict the value of the other variable

Correlation r

for a linear association between two quantitative variables this measures the direction and strength of an association