(* PS4.1, using DATA4-1, for reproducing Table 4.2 *)
ols price const sqft
(* add bedrms - Model B *)
add bedrms  
(* add bath rooms also - Model C *)
add baths  
(* model with only constant - Model D *)
ols price const  
(* model without a constant *)
ols price sqft 
(* The following commands will be useful for Example 4.6 on Wald F-test *)
ols price const sqft bedrms baths  
(* retrieve ESS *)
genr ESSU = $ess
(* retrieve d.f. *)
genr DFU = $df
(* restricted model R *)
ols price const sqft 
(* retrieve ESS *)
genr ESSR = $ess
(* retrieve d.f. *)
genr DFR = $df
(* number of restrictions *)
genr NR = DFR - DFU
(* compute Fc *)
genr Fc = (ESSR - ESSU)*DFU/(ESSU*NR)
(* learn about pvalue *)
help pvalue
(* compute pvalue - F-distribution is 4 *)
pvalue F NR DFU Fc
(* Model U again *)
ols price const sqft bedrms baths  
(* use omit command and note that Fc and pvalue are given at the end *)
omit bedrms baths
(* commands for Example 4.2 *)
genr sqft2 = sqft-2000
genr bedrms2 = bedrms-4
genr baths2 = baths-2.5
ols price 0 sqft2 bedrms2 baths2