Regression statistics will typically include an R-squared value. The closer to 1 this is, the stronger the correlation between the returns of the two stocks.

When I'm trying to determine which R technique to use, I start by mentally imagining the source data in an Excel spreadsheet. If there is one column that I'm particularly interested in, and that ...

Figure 1: The results of multiple linear regression depend on the correlation of the predictors, as measured here by the Pearson correlation coefficient r (ref. 2).