*
* Example NUPOWER.DAT from pp 649-651
*
open data nupower.dat
calendar 1960
data(format=free,org=columns) 1960:1 1993:1 year gigawatts
*
set ytr = log(gigawatts/(350-gigawatts))
set time = t
*
linreg ytr
# constant time
*
set fitfore = 350.0/(1+exp(-%beta(1)-%beta(2)*t))
set error = gigawatts-fitfore
*
print(picture="*.###") / gigawatts fitfore error