Describing relationships in quantitative data

If we want to explore a relationship between two quantitative variables, we make a scatterplot of the data. The fun doesn't stop there. We describe pattern, talk about the type of correlation we see, and sometimes fit a line to the data so we can use the pattern to make predictions.
See how you score on these 18 practice questions

Residuals measure how far away each data point is from a line that has been fit to the data in a scatterplot. A least-squares regression line tries to fit the data the best it can by making these residuals as small as possible, and we can measure how well a line fits using r-squared. This tutorial explores a few of the more advanced topics in linear regression.