i don't see a tradeoff between n for sample and k for # of items as being
really THE or AN issue
you don't really consider n for sample (though having larger is nicer) ...
when you are contemplating the general size of the reliability coefficient
you are targeting to
that is ... you don't say ... well, i can only "run" 10 Ss so, i need twice
the number of items ... or, since i can have 400 Ss i only NEED 8 items
the real benefit that larger n might have is that it would produce
probably a little more test score variance ... which might be helpful in
the calculation of alpha ... making it potentially a bit larger
now, the stability of the alpha coefficient ... that is a different matter ...
At 12:08 PM 2/28/01 +0100, Nicolas Sander wrote:
>How is Cronbach's alpha affected by the sample size apart from questions
>related to generalizability issues?
>
>Ifind it hard to trace down the mathmatics related to this question
>clearly, and wether there migt be a trade off between N of Items and N
>of sujects (i.e. compensating for lack of subjects by high number of
>items).
>
>Any help is appreciated,
>
>Thanks, Nico
>--
>
>
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_________________________________________________________
dennis roberts, educational psychology, penn state university
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