set more off
clear

*****chapter$ ex4.1********
use "L:\Alma Kudebayeva\Fall2017\ECN5012 Econometrics\Chapter4\eaef21.dta", clear


gen z=1/SIBLINGS

su S SIBLINGS
tab S
tab SIBLINGS

reg S z

predict S1

twoway (fpfit S1 SIBLINGS)

********Ex4.2************************
gen LGS=ln(S)
gen LGSM=ln(SM)

reg LGS LGSM 
***** EX4.3*************************
gen LGS=ln(S)
reg LGS SM 



******Ex4.8************************************
use "L:\Alma Kudebayeva\Fall2017\ECN5012 Econometrics\Chapter4\eaef21.dta", clear

gen LGEARN=ln(EARNINGS)

gen SA=S*ASVABC
reg LGEARN S EXP ASVABC SA if MALE==1

su S EXP ASVABC if MALE==1
gen S1=S-13.7
gen ASVABC1=ASVABC-52.11
gen SA1=S1*ASVABC1

reg LGEARN S1 EXP ASVABC1 SA1 if MALE==1

*********Ex4.4**************************


 use "L:\Alma Kudebayeva\ECN3184Econometric_methods_Fall2015\Chapter4\ces.dta", clear 

reg CLOT EXP if CLOT>0

gen LGCLOT=ln(CLOT)
gen LGEXP=ln(EXP)

reg LGCLOT LGEXP

reg LGCLOT  EXP

reg FDHO EXP if FDHO>0
gen LGFDHO=ln(FDHO)
reg LGFDHO LGEXP

********Ex 4.5*************
gen LGEXP=ln(EXP)

gen LGFDHO=ln(FDHO)
gen LGSIZE=ln(SIZE)
reg LGFDHO LGEXP LGSIZE

*******************************************************************************************************
****RESET tests************************
regress LGFDHO LGEXP LGSIZE
estat ovtest

 
************Ex4.10***************************

use "L:\Alma Kudebayeva\Fall2017\ECN5012 Econometrics\Chapter4\eaef21.dta", clear
sum LGEARN

gen EARNSTAR = EARNINGS/exp(2.782847)
gen LGEARNST = ln(EARNSTAR)

reg  EARNSTAR  S EXP 
predict res1, residual 


reg LGEARNST  S EXP 

predict res, residual

*******Ex. 4.12**************************

gen SMSQ=SM*SM

reg S  SM SMSQ