- Thread starter chaimae
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You could try finding the correlation matrix between the questions to see if they fall naturally into two groups, or do some other sort of multivariate discriminant analysis.

You could try finding the correlation matrix between the questions to see if they fall naturally into two groups, or do some other sort of multivariate discriminant analysis.

I'm in the learning phase and I'm applying at the same time, if in my case I find questions that fall naturally into two groups, do I apply Cronbach's alpha for each of these two groups; is that the idea?

and can you clarify more about doing other sort of multivariate discriminant analysis? is that in this case I won't need to specify cronbach's alpha?

thank you

Chrobach's alpha is usually used to show that the total score on a particular set of related questions is a good measure of a particular construct (eg self confidence) and so that the total score on that set can be used as a reliable instrument to measure that construct.

If your questions fall naturally into two groups measuring different things you are likely to get a low alpha overall. So a low alpha suggests to me that says that you are perhaps measuring two different concepts. If you can separate these groups and they both have high alphas then you have two reliable instruments that measure different things. What those different things are may not be obvious. You will still need alpha to justify the questions in each group if you want other people to trust or use your newly invented scale.

Determining the groups of related questions, if they exist, can be done in a variety of ways. Look up cluster analysis and discrimination analysis if you think there may be two different scales. If this is an important project, like a masters or PhD, or a journal paper, I suggest you talk to a social science statistician for an hour. It would be money well spent. kat