For the reading data in the file read.dat, use the S-PLUS function runm3d to investigate the shape of the regression surface when predicting the 20% trimmed mean of WWISST2 (the data in column 8) with...

For the reading data in the file read.dat, use the S-PLUS function runm3d to investigate the shape of the regression surface when predicting the 20% trimmed mean of WWISST2 (the data in column 8) with RAN1T1 and RAN2T1 (the data in columns 4 and 5).

The data in the lower left panel of Figure 11.5 are stored in the file agegesell.dat. Remove the two pairs of points having the largest x value, and create a running-interval smoother using the data that remain.