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Thread: Do I have to test normality?

  1. #1
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    Smile Do I have to test normality?




    I have an experiment contains 10 students and 2 experts. I want to test if the average of students evaluation for the 1st question is similar to experts average. the question answer is scale from 1~5.
    - do I have to test if students answer is normally distributed? you should know the students are the whole students in the class and they are not random sample.
    - I plan to do one sample t-test for comparing students median and experts median.

    thanks in advance

  2. #2
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    Re: Do I have to test normality?

    - do I have to test if students answer is normally distributed?
    You probably have an ordinal scale, so normality isn't an issue.
    And with n=10, any normality test has too small statistical
    power to be useful. If you sticked to nonparametric tests, you'd
    be on the safe side.

    - I plan to do one sample t-test for comparing students median and experts median.
    t-tests are for means, not for medians. You could do a
    Mann-Whitney U-test, although I don't know
    whether it is at all possible to reach the usual
    p < 0.05 criterion if one of the groups has only
    n=2.

    With kind regards

    K.

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    Re: Do I have to test normality?


    thanks Karabiner, and one thing more, if I have more than one question such as 20 and experts answer all and each student answer 5. do I have to do Kappa for the experts or I can just take the average.

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