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Thread: Using standard deviations to group participants

  1. #1
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    Using standard deviations to group participants




    I have scores from 83 participants, and would like to group them in to high, medium and low. The data is normally distributed.

    I thought that I could allocate to groups using standard deviations, for example, 1.5 sd above is high, 1.5 below is low.

    But this is where I get stuck.

    If my mean is 49.17, and the sd 33.61, then what would my cut off scores be for each group?

    I thought (33.61/2) + 33.61 to get 1.5 sd = 50.42, so my cut off would be 49.17 + 50.42 = 99.59.

    But is that incorrect? Only 4 of my participants scored over 99.59.

    Any help gratefully received! Thanks.

  2. #2
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    Re: Using standard deviations to group participants

    You can use percentages. For example, 25% lower and upper 75%.

  3. The Following User Says Thank You to Masteras For This Useful Post:

    charlie007 (03-05-2017)

  4. #3
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    Re: Using standard deviations to group participants


    Ah, brilliant. Thank you!

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