I wrote a very simple program and run it on both Stata 7 intercool and Stata 8 SE, but they give me different answers.
The reason is that they drop different variables.
I wonder why is this. Should they do the same job since I use the exact same program and data set?
Program:
clear
set memory 200m
***set maxvar 2048
set more off
set rmsg on
set logtype text
set linesize 200
***Course 32 matching estimator
use pdp_matching.dta, clear
keep coalition_pool verbal_sat math_sat eop_status hs_gpa father_educ mother_educ language_code english non_english ethnic admit_major math_physics econ_business chemistry biology engineering c32_lecture c32_times_taken c32_year c32_term c32_num_grade c32_math_98 c32_pdp_ids c32_pdp_ids_not_pass c32_slc_adjunct c32_slc_adjunct_not_pass pdp slc pdp_coalition_pool
drop if coalition_pool == .
drop if verbal_sat == .
drop if math_sat == .
drop if eop_status == .
drop if hs_gpa == .
drop if father_educ == .
drop if mother_educ == .
drop if language_code == .
drop if english == .
drop if non_english == .
drop if ethnic == .
drop if ethnic == 9
drop if admit_major == .
drop if math_physics == .
drop if econ_business == .
drop if chemistry == .
drop if biology == .
drop if engineering == .
drop if c32_lecture == .
drop if c32_year == .
drop if c32_term == .
drop if c32_num_grade == .
drop if slc == 1
keep if ethnic == 1
keep if c32_num_grade < 5 | c32_num_grade==6 | c32_num_grade==7
replace c32_num_grade=0 if c32_num_grade<=1.3 | c32_num_grade==7
replace c32_num_grade=1 if c32_num_grade>=1.7 | c32_num_grade==6
generate same_class = c32_year*100 + c32_term*10 + c32_lecture
local varlist_1 = "math_sat eop_status hs_gpa father_educ mother_educ english non_english math_physics econ_business chemistry biology engineering"
local varlist_2 = "verbal_sat"
foreach var of local varlist_1 {
egen `var'_max = max(`var')
egen `var'_min = min(`var')
if `var'_max ~= `var'_min {
local varlist_2 = "`varlist_2' `var'"
di "keep `var'"
}
else {
display "drop `var'"
}
}
display "Finish dropping"
egen pdp_sum = sum(pdp)
describe
}
log close
Please find the data on:
http://are.berkeley.edu/~fan/imbens/
Maoyong Fan
University of California
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