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***SOCI 420: ADVANCED METHODS OF SOCIAL RESEARCH
***HYPOTHESIS TESTING IV: CHI SQUARE (chapter 11)
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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\Stata11.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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***GENERATING VARIABLES
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***Generate 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

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***CHI SQUARE
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***It would be incorrect to use fweight,
***because you would get statistical significance
***by indicating to the test that you have
***more observations than what was actually collected

***Weights that preserve sample size (aweight, pweight)
***are not allowed in Stata to estimate chi square

***Thus, estimate chi square using the
***complex survey design command (svy)

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***Opinion about immigration by sex
***Use column percentages with weight
tab letin1 sex [aweight=wtssnrps], col
tab letin1 sex [aweight=wtssnrps], col nofreq // column percentage

***Observed frequencies (fo)
tab letin1 sex // sample size

***Expected frequencies (fe)
tab letin1 sex, exp nofreq

***Chi square option works only without weights
tab letin1 sex, chi col
tab letin1 sex, chi col nofreq

***Use the chi square estimated with complex survey design
svy: tab letin1 sex, col // chi square test

***Use missing cases from this table
tab letin1 sex, m // missing cases

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***Opinion about immigration by political party
***Use column percentages with weight
tab letin1 democrat [aweight=wtssnrps], col
tab letin1 democrat [aweight=wtssnrps], col nofreq // column percentage

***Observed frequencies (fo)
tab letin1 democrat // sample size

***Expected frequencies (fe)
tab letin1 democrat, exp nofreq

***Chi square option works only without weights
tab letin1 democrat, chi col
tab letin1 democrat, chi col nofreq

***Use the chi square estimated with complex survey design
svy: tab letin1 democrat, col // chi square test

***Use missing cases from this table
tab letin1 democrat, m // missing cases

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***CLOSING COMMANDS
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***Save data
save "$data\Stata11.dta", replace

***Save log
log close