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***SOCI 420: ADVANCED METHODS OF SOCIAL RESEARCH
***HYPOTHESIS TESTING II: THE TWO-SAMPLE CASE (chapter 9)
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***CLEAR MEMORY
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clear all

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***CREATE SHORTCUTS AND LOG FILE
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***Shortcut for folders
global codes  = "H:\course\codes"
global data   = "H:\course\data"
global output = "H:\course\output"

***Start saving results window
log using "$codes\Stata09.log", replace text

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***OPENING COMMANDS
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***Tell Stata to not pause for "more" messages
set more off

***Open 2021 GSS
use "$data\GSS2021.dta", clear

***Complex survey design
svyset [weight=wtssnrps], strata(vstrat) psu(vpsu) singleunit(scaled)

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***TWO-SAMPLE t-TEST
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***Mean of personal income by sex
tabstat conrinc, by(sex)

***t-test of personal income by sex
ttest conrinc, by(sex)

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***TWO-SAMPLE TEST OF PROPORTIONS
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***Number of immigrants to America nowadays should be
tab letin1, m
tab letin1, m nolabel

***Create dummy variable for pro-immigrants vs. anti-immigrants
***"remain the same as it is" will be missing
gen proimmig=.
  replace proimmig=1 if letin1==1 | letin1==2
  replace proimmig=0 if letin1==4 | letin1==5

tab letin1 proimmig, m
tab proimmig

***Create dummy variable for Democrats vs. Republicans
***"Independents" will be missing
tab partyid, m
tab partyid, m nolabel

gen democrat=.
  replace democrat=1 if partyid>=0 & partyid<=2
  replace democrat=0 if partyid>=4 & partyid<=6

label variable democrat "Political party"
label define party 1 "Democrats" 0 "Republicans"
label values democrat party

tab partyid democrat, m
tab democrat

***Proportion of pro-immigrants by political party
tab proimmig democrat, col nofreq
tabstat proimmig, by(democrat)

***Test of proportions of pro-immigrants by political party
prtest proimmig, by(democrat)

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***CLOSING COMMANDS
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***Save data
save "$data\Stata09.dta", replace

***Save log
log close