The Statistics::LineFit module does weighted or unweighted least-squares
line fitting to two-dimensional data (y = a + b * x).  (This is also
called linear regression.) In addition to the slope and y-intercept, the
module can return the square of the correlation coefficient (R squared),
the Durbin-Watson statistic, the mean squared error, sigma, the t
statistics, the variance of the estimates of the slope and y-intercept,
the predicted y values and the residuals of the y values.