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I noticed that someone included the total score of each item when calculating the Cronbach's alpha of the questionnaire. I don't know the reason for this?

Original link https://stackoverflow.com/questions/55741723/psychalpha-detailed-interpretation-of-the-output

Total score items within the red box

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I'm hoping someone can help me understand the difference and implications of doing this and not doing it. Thanks!

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You would not want to include the total score when computing alpha for a set of items if the total score is defined as the sum (or mean) of the items. The total score (trivially) covaries with the items that constitute the score, and so you would end up with an incorrect estimation of alpha (reliability).

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  • $\begingroup$ Thank you for your help. Additionally, I wonder under what conditions this is allowed. $\endgroup$
    – user388013
    Jul 17, 2023 at 1:13
  • $\begingroup$ I don't think it would ever be appropriate to include the total score in the computation of alpha for composite reliability if the composite (total score) is a function of the items. $\endgroup$ Jul 17, 2023 at 10:33
  • $\begingroup$ thank you again for your help $\endgroup$
    – user388013
    Jul 19, 2023 at 1:08

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