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i have drafted 51 items that are supposed to measure 9 distinct but related constructs, and have collected data on this questionnaire from 530 people. ultimately, i want to use these data for a sem.

however, given that i devised the items myself, they seem to be far away from being perfect indicators of the constructs / latent variables that i intended to measure. therefore, it seems to me that i should make a selection of the 51 items before i proceed. all the criteria for item selection that i found in the literature (e.g., item-total correlation, item difficulty, item variance) seem to help only for choosing items for a unifactorial model, but not for the 9-factorial model that i have in mind, because they neglect the items' relationships with related concepts that would result in high cross-loadings.

therefore i have looked at a table of bivariate correlations among all items and have selected those items that show a) high correlations with the other items from their own hypothesized factor, and b) low correlations with items hypothesized to "belong" to other factors. this resulted in a list of 35 items that will be used for further analyses.

do you have any objections to this strategy?

heinbl0ed
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Doing what you want to do is a complex process called test development. You should probably consult an expert in that, if you want it to be done right. However, I'd say that your first step ought to be factor analysis.

Peter Flom
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  • I am looking for an appropriate measurement model for my data. You may call this test development. Given that I have devised the items myself, and they haven't been used before, I think it is fair to deselect those prior to factor analysis that were obviously interpreted differently by participants. Given this, would you recommend other strategies for this preselection? – heinbl0ed Sep 24 '18 at 13:27
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    As I said, this is a complex process. I wrote a book chapter about it. I don't think it can be fully covered in an answer on CV. – Peter Flom Sep 24 '18 at 13:29
  • Alright. I'd be happy to hear additional opinions on the topic though as I expected asking questions to be the purpose of CV. – heinbl0ed Sep 24 '18 at 13:42
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    Asking questions is fine! But sometimes the answer is "that's too complex to be answered here" – Peter Flom Sep 24 '18 at 14:38