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Thread: Chi square test: how to solve this one ?

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    Chi square test: how to solve this one ?




    A dentist observed that most of the patients have cavities in their teeths at the right-side of their mouth. (see data: observed values)

    The hypothesis is that most of the people are right-handed and therefore they brushing their teeths better on the left-side then on the right-side of their mouth.

    I struggle a bit since I become a lower value then the textbook, the answer should be 8,2791 (Ha). I'm unsure about my expected values. In one case they where all the same:
    50/4 = 12,5

    Then I have expected values that are 4 times different for each cell:
    E = 20*19/50 = 7,6
    E = 30*19/50 = 11,4
    E = 20*31/50 = 12,4
    E = 30*31/50 = 18,6
    That would provide me as answer 6,8477 instead of 8,2791.

    Is there someone who is smarter then me

    Any help is very welcome !
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    Re: Chi square test: how to solve this one ?


    This is the only right answer: Chi square equals 5,3798
    You work with frequenties instead of numbers so this is the solution:
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