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Support #1859

sample size loss due to weighting

Added by Caroline Kienast von Einem about 1 year ago. Updated 5 months ago.

Status:
Resolved
Priority:
Normal
Category:
Weights
Start date:
02/20/2023
% Done:

100%


Description

Hi,

I am aware that weighting will affect and alter the sample size of the analysis, however, I am working with a pooled sample of participants from wave 3-6 and when I specify a weighted model my sample drops from ~45k to 27k. This seems quite significant, particularly once I start to investigate subgroup characterstics..

Would you be able to confirm whether a drop by ~20k is normal once weighting is applied ( ai am using the longitudinal wave f weight "f_indinub_lw" / whether the below STATA code makes you think it is instead an error with my coding?

STATA CODE:

//Open wave 6:
use f_hidp f_psu f_strata pidp f_sex_dv f_age_dv f_indinub_lw using "$inpath\f_indresp", clear

save "test", replace

foreach w in c d e {

// Extract the variables needed
use "$inpath/`w'_indresp", clear
isvar pidp `w'_addrmov_dv `w'_adcts `w'_distmov_dv `w'_mvyr `w'_mvever `w'_plnowy4
keep `r(varlist)'
// save each wave specific file
save `w'junk.dta, replace
}

// Open the file for wave f and then add the rest of the wave specific files
use "test", clear
foreach w in c d e {
merge 1:1 pidp using `w'junk.dta
drop _merge
}

save "test", replace

// get rid of unwanted temporary files
foreach w in c d e {
erase `w'junk.dta
}

mvdecode _all, mv(-9/-1)

//I only want those with data at wave 6
drop if f_hidp==.

tabulate f_sex_dv // -> n= 45,186

svyset f_psu , strata(f_strata) singleunit(scaled)|| pidp, weight(f_indinub_lw)
svy: tabulate f_sex_dv, count col // -> n=27,094

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