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st: vreverse when not all possible values of a variable are used by respondents


From   "Christopher W. Ryan" <cryan@binghamton.edu>
To   statalist <statalist@hsphsun2.harvard.edu>
Subject   st: vreverse when not all possible values of a variable are used by respondents
Date   Thu, 31 May 2007 13:23:19 -0500

I am analyzing a survey that contains the Toronto Alexithymia scale, the
Interpersonal Reactivity Index, and the Psychological Mindedness Scale.
These are typical ordinal "Likert-type" scales, with values on each item
ranging from 1-5, 0-4, etc, depending on the scale.

Many of the items contained no responses at one end of the scale or the
other. For example, on many items, none of the respondents chose 0, 1,
or 2; everyone chose 3 or above.

I used the vreverse package to reverse the items that needed reversing,
but I wonder now if that was inappropriate when the full range of values
was not used by respondents. If an item *can* range from 1 to 5, but
only 3-5 were actually *used*, would the original 5s be recoded to 1s in
the new variable (the desired behavior), or into 3s (undesired)?

I think it is the latter case:

sysuse auto, clear
label define rep 1 one 2 two 3 three 4 four 5 five
label values rep78 rep
preserve
vreverse rep78, generate(flipped)
tab rep78, nolabel
tab flipped, nolabel
tab rep78 flipped, nolabel

*now drop all the cases where rep78 is less than 3, and do it all again.
restore
drop if rep78<3
vreverse rep78, generate(flipped)
tab rep78, nolabel
tab flipped, nolabel
tab rep78 flipped, nolabel

Do I understand the behavior of vreverse properly?

Thanks.

--Chris

-- 
Christopher W. Ryan, MD
SUNY Upstate Medical University Clinical Campus at Binghamton
40 Arch Street, Johnson City, NY  13790
cryanatbinghamtondotedu
PGP public keys available at http://home.stny.rr.com/ryancw/

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