? P&R Exercise 15.1

option limwarn=0;
freq m; smpl 86:1 95:12;
read(file='\tsp\prhb\datadisk\ex151.xls', format=excel) rt531r;
sales=rt531r;
lsales=log(sales);
smpl 86:1 96:1 ;      ? Include the forecasting period.
trend (start=0) time; ? Start time at zero like P&R.

? Simple time trend model, level and log.

olsq sales c time;
forcst linear;
olsq lsales c time;
forcst llinear;
llinear=exp(llinear);

? Simple autoregression, level and log.

smpl 86:2 96:1 ;        ? Need lagged sales for these two.
olsq sales c sales(-1);
forcst autor;
olsq lsales c lsales(-1);
forcst lautor;
lautor=exp(lautor);

smpl 95:1 96:1 ;
print  sales linear llinear autor lautor;

stop;end ;