Handling missing values in Stata

This allows replicating the analyses in Allison (2002, pp. 68-73).

// MI example 2
use spanking age educ income91 sex race marital region childs god using "C:\Users\User\Dropbox (FAMSIZEMATTERS)\methods and data\GSS1994.dta", clear
recode spanking (1 = 4) (2 = 3) (3 = 2) (4 = 1)
generate female  = (sex == 2)
generate black   = (race == 2)
recode income91 ( 1 =   500) ( 2 =  2000) ( 3 =  3500) ( 4 =  4500) ( 5 =  5500) /// 
                ( 6 =  6500) ( 7 =  7500) ( 8 =  9000) ( 9 = 11250) (10 = 13750) ///
                (11 = 16250) (12 = 18750) (13 = 21250) (14 = 23750) (15 = 27500) ///
                (16 = 32500) (17 = 37500) (18 = 45000) (19 = 55000) (20 = 67500) ///
                (21 = 75000), gen(income)
replace income = income / 1000

generate nochild = (childs == 0)         if !missing(childs)
generate nodoubt = (god == 6)            if !missing(god)
generate nevmar  = (marital == 5)        if !missing(marital)
generate divsep  = inlist(marital, 3, 4) if !missing(marital)
generate widow   = (marital == 2)        if !missing(marital)
generate east    = inlist(region, 1, 2)
generate midwest = inlist(region, 3, 4)
generate south   = inlist(region, 5, 6, 7)

misschk spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow

eststo clear
eststo: ologit spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow

drop if missing(marital)

preserve
recode educ (.d .n = .) 
recode spanking (.d .i .n = .)

mi set mlong
mi register imputed spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow

mi impute mvn spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow, ///
   add(5) burnin(500) burnbetween(200) emlog emoutput

foreach x of varlist female black nodoubt nochild east midwest south nevmar divsep widow {
   replace `x' = 0 if `x'  < .5 & _mi_m != 0
   replace `x' = 1 if `x' >= .5 & _mi_m != 0
}

replace spanking = 1 if                   spanking < 1.5 & _mi_m != 0
replace spanking = 2 if spanking >= 1.5 & spanking < 2.5 & _mi_m != 0
replace spanking = 3 if spanking >= 2.5 & spanking < 3.5 & _mi_m != 0
replace spanking = 4 if spanking >= 3.5                  & _mi_m != 0

eststo: mi estimate, post: ologit spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow
restore

preserve
recode educ (.d .n = .) 
recode spanking (.d .i .n = .)

mi set mlong
mi register imputed spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow

mi impute chained (mlogit) spanking (regress) income educ (logit) nodoubt nochild = female black age east midwest south nevmar divsep widow, ///
   add(5) burnin(20) force

eststo: mi estimate, post: ologit spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow
restore

preserve
mi set mlong
mi register imputed spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow

drop if missing(spanking)
mi impute chained (mlogit) spanking (regress) income educ (logit) nodoubt nochild = female black age east midwest south nevmar divsep widow, ///
   add(5) burnin(20) force

eststo: mi estimate, post: ologit spanking female black income educ nodoubt nochild age east midwest south nevmar divsep widow
restore

esttab, wide se keep(spanking:) nonumbers modelwidth(15) ///
  mtitle("Listwise deletion" "Normal data augmentation" "Sequential regression" "Seq. regression w/out missings") ///
  title(Coefficient estimates and standatd errors for cumulative logit models predicting SPANKING)

Reference

Allison, Paul D. 2002. Missing Data. Sage. doi: 10.4135/9781412985079

Using additional variables in multiple imputation

This allows replicating Table 6.2 in Allison (2002).

// Table 6.2
use "https://statisticalhorizons.com/wp-content/uploads/college.dta", clear

mi set mlong
mi register imputed csat act gradrat

eststo clear
eststo: regress csat


// Impute using ACT
mi impute mvn csat act, ///
   add(5) burnin(500) burnbetween(200) emlog emoutput

eststo: mi estimate, post: regress csat

// PCT25 is missing altogether in the data

// Impute using ACT and GRADRAT
mi impute mvn csat act gradrat, ///
   add(5) burnin(500) burnbetween(200) emlog emoutput

eststo: mi estimate, post: regress csat

esttab, not se mtitle("No imputation" "ACT" "ACT and GRADRAT") nonumbers ///
        coeflabel(_cons "Mean") modelwidth(15) title("Mean (and standard errors) of CSAT with different variables used in imputation")

Reference

Allison, Paul D. 2002. Missing Data. Sage. doi: 10.4135/9781412985079

Interactions in multiple imputation

This replicates the analyses for Table 6.1 for Allison (2002).

// Table 6.1

// Method 1
use "https://statisticalhorizons.com/wp-content/uploads/college.dta", clear

mi set mlong
mi register imputed gradrat csat private lenroll stufac rmbrd act

mi impute mvn gradrat csat private lenroll stufac rmbrd act, ///
   add(5) burnin(500) burnbetween(200) emlog emoutput

eststo clear
eststo: mi estimate, post: regress gradrat lenroll i.private##c.csat stufac rmbrd 

// Method 2
use "https://statisticalhorizons.com/wp-content/uploads/college.dta", clear

mi set mlong
mi register imputed gradrat csat lenroll stufac rmbrd act

mi impute mvn gradrat csat lenroll stufac rmbrd act, ///
   add(5) burnin(500) burnbetween(200) emlog emoutput ///
   by(private)

eststo: mi estimate, post: regress gradrat lenroll i.private##c.csat stufac rmbrd 

// Method 3
use "https://statisticalhorizons.com/wp-content/uploads/college.dta", clear

generate privateXcsat = private * csat

mi set mlong
mi register imputed gradrat csat private lenroll stufac rmbrd act privateXcsat 

mi impute mvn gradrat csat private lenroll stufac rmbrd act privateXcsat, ///
   add(5) burnin(500) burnbetween(200) emlog emoutput

eststo: mi estimate, post: regress gradrat lenroll i.private csat privateXcsat stufac rmbrd 

esttab, not p wide nostar noobs varlabel(_cons "Intercept") ///
        order(_cons csat lenroll stufac 1.private rmbrd) ///
        rename(privateXcsat 1.private#c.csat) varwidth(25) nobaselevels ///
        title(Regression with interaction terms--three methods) ///
        mtitle("Method 1" "Method 2" "Method 3") nonumbers

Reference

Allison, Paul D. 2002. Missing Data. Sage. doi: 10.4135/9781412985079