An article published in Geography (July 1980) used multiple regression to predict annual rainfall levels in California. Data on the average annual precipitation (y), altitude (x,), latitude (x,), and distance from the Pacific coast (x,) for 30 meteorological stations scattered throughout California are listed in the table on page 597.

Initially, the first-order model y = Po + Plxl +

P,x2 t P3x3 + E was fit to the data.The SAS printout of the analysis is provided on page 596.

a. Is there evidence that the first-order model is useful for predicting annual precipitation y? Test using a = .05.

b. Ninety-five percent prediction intervals for y are shown at the bottom of the printout. Locate and interpret the interval for the Giant Forest meteoro logical station (station #9).