Question: 1. Show that the simple regression line of y against x coincides with the simple regression line of x against y if and only if r = 1 (where r is the sample correlation coefficient between x and y).
2. In the regression model y1 = α + βx1 + µ if the sample mean of x¯ of x is zero, show the covt(α^, β^) = 0, where α^ and β^ are the least squares estimators of a and ~.