# script to compute NLS of PoE consumption Example
open "i:\Program Files\gretl\data\poe\consumption.gdt"
# run initial OLS
ols CONS 0 INC
genr ssebak = $ess
genr ssediff = 1
genr b = $coeff(INC)
genr g = 1
# iterate OLS till the error sum of squares converges
loop while ssediff > .00001
   # form the linearized variables
   genr C_bar = CONS + g * b * INC^g * log(INC)
   genr x1 = INC^g
   genr x2 = b * INC^g * log(INC)
   # run OLS 
   ols C_bar 0 x1 x2 --print-final --no-df-corr --vcv
   genr b = $coeff(x1)
   genr g = $coeff(x2)
   genr sse = $ess
   genr ssediff = abs(sse - ssebak)/ssebak
   genr ssebak = sse
endloop 
# print parameter estimates using their "proper names"
noecho
printf "alpha = %g\n", $coeff(0)
printf "beta  = %g\n", b
printf "gamma = %g\n", g

genr se_b = $stderr(x1)
genr se_g = $stderr(x2)

genr tv1 = b/se_b
genr tv2 = g/se_g