MathCastle
Statistics & DataSuperchallengeTwo Variables

Two Variables · Superchallenge problem

A least-squares line is fitted to a data set in which xx and yy have correlation r=0.6r = 0.6. Each yy-value is then replaced by y∗=y^+2ey^* = \hat y + 2e, its predicted value plus twice its residual. What is the exact correlation between xx and y∗y^*?