Based on the regression equation, y = 49.4 - 0.313 x, where x is lattitude and y is average estimated january temperature, the expected temp fo Pittsburg, at a lattitude of 40, is 49.4 - (0.313 * 40), or 36.88 degrees fahrenheit. This differs, by 11.88 deg f from the measured report of 25 deg f for January tepuratues in Pittsburg.