How to Generate an Alpha Coefficient Variable?

[Louisa Roberts]

Dear Stata Forum,

I’m using Stata 13 and working with a large pooled time-series cross-section dataset. My cases are individuals who were surveyed in different country-years. What I need help with is: I want to generate a new variable that is the country-year-specific Cronbach’s alpha coefficient for a scale I’m playing around with. I’ve succeeded in computing the country-year-specific alpha coefficient. See below:

by country year: alpha rauth indep imag obedneg proud frd say abjust hojust divjust wpoly uni jobs3, std asis

But, I don’t know how to turn the resulting alpha coefficients into a new variable. I think that requires knowledge of Stata programming, with which I’m barely familiar.

I’d absolutely appreciate any thoughts!

Best,
Louisa

[Nick Cox]

help statsby

[Louisa Roberts]

Thanks very much, that worked! Statsby rocks.

Here's what I did:

statsby alpha7=r(alpha), by(S003 S020) saving(alpha7_150331): alphawgt rauth indep imag obedneg proud sexsc womsc [aw=S017] if minrauth<. & ///
minindep<. & minimag<. & minobedneg<. & minproud<. & minabjust<. & minhojust<. & mindivjust<. & minwpoly<. & ///
minuni<. & minjobs3<., std asis

Note that instead of using alpha I use a slightly different user-written command called alphawgt that allows for the use of weights.

Louisa

[Clyde Schechter]

Completely as an aside, that lengthy -if- condition can be written somewhat more compactly as

...if !missing(minrauty, minindep, minimag, minobedneg, minproud, minabjust, minhojust, mindivjust, minwpoly, minuni, minjobs3)

[Louisa Roberts]

Thanks for that tip!