Relationship between Pearson correlation coefficient and the r-squared from linear regression

Simply put, if you take the square root of the r-squared value, which can be easily obtained in Excel, the outcome equals to the Pearson correlation coefficient.

Here's my R code to test this:


x<-rnorm c="" font="" nbsp="">
y<-rnorm c="" font="">
mdl <- font="" lm="" x="" y=""># linear regression model
r = summary(mdl)$r.squared # the r-squared value from linear regression
rp = cor.test(x,y, method='pearson')$estimate # rp is the Pearson correlation coefficient
sqrt(r) == rp