Posted by
Steve Simon, P.Mean Consulting on
Dec 29, 2009; 5:07pm
URL: http://spssx-discussion.165.s1.nabble.com/cronbach-alpha-for-binary-responses-tp1086058p1086059.html
Eins Bernardo wrote:
> May I know if Cronbach alpha can be used as measure of reliability for a
> correct/wrong response (coded 0 or 1) items? I want to use it for each
> subscale (with 8 items each) of my instrument with three scales. Thank
> you for your comments.
PASW Statistics/SPSS will allow you to calculate Cronbach's alpha for
this type of data, but the more important question is whether you can
get those results published. As far as I know, Cronbach's alpha does not
make any distributional assumptions. There may be problems with
artificial bounds being placed on Cronbach's alpha by the discrete
nature of your data. This might make it impossible for this measure to
get very close to +1, depending on the degree of skewness of your binary
variables.
I suspect that your peer reviewers would give you a hard time about this
measure, although there isn't much in the way of alternatives available
here. I wouldn't fuss about it, but I am rarely asked to be a
peer-reviewer.
It costs nothing other than a few electrons to make the calculation. So
put it in, mention the binary nature of your data as a limitation and
see what the peer-reviewers say.
I hope this helps.
--
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