For the reading data in file read.dat, let x be the data in column 2 (TAAST1), and suppose it is desired to predict y, the data in column 8 (WWISST2). Speculate on whether there are situations where it would be beneficial to use x 2

to predict y taking into account the value stored in column 3 (SBT1). Use the functions in this chapter to address this issue.