pause on
infile x y using ovfit
gen samp=1 if _n<7
gen samp2=1 if _n<40
sort x
scatter y x
pause
sort x
scatter y x if samp==1
pause
gen x2=x*x
gen x3=x*x2
gen x4=x*x3	
gen x5=x*x4
gen x6=x*x5
gen x7=x*x6
gen x8=x*x7
reg y x x2 x3 x4 x5  if samp==1
predict yhat
scatter y yhat x if samp==1
pause
scatter y yhat x 
pause
reg y x  if samp==1
predict yhat2
scatter y yhat2 x 
reg y x if samp2==1
predict yh1
reg y x x2 x3 if samp2==1
predict yh2
reg y x x2 x3 x4 x5 if samp2==1
predict yh3
scatter y yh1 yh2 yh3 x
pause
gen uu=uniform()
sum uu
pause
gen cut=0
replace cut=1 if uu>0.5
replace cut=. if samp2==.
sum cut
pause
reg y x if cut==0
predict yc1
label variable yc1 "Forecast Model 1"
reg y x x2 x3 if cut==0
predict yc2
label variable yc2 "Forecast Model 2"
reg y x x2 x3 x4 x5 x6 x7 x8 if cut==0
predict yc3
label variable yc3 "Forecast Model 3"
scatter y yc1 yc2 yc3 x if cut==1
pause
gen fit1=(y-yc1)*(y-yc1) if cut==1
gen fit2=(y-yc2)*(y-yc2) if cut==1
gen fit3=(y-yc3)*(y-yc3) if cut==1
sum fit1 fit2 fit3