iSixSigma

Sample Size

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  • #54202

    chris reid
    Participant

    I dont now how to estimate the sample size required to prove a difference on what I think is proportion data.
    To be more specific currently the area I work in consistantly recieves 4.5k calls a month and I know 20% of these are due to a particular problem. My sample size is 50. Where could I go on minitab to work out how large a sample I need to show a 10% reduction.
    Hope you can help.

    Thanks.

    0
    #194208

    Prabhu V
    Participant

    Hi,

    Please follow the below formula on your case

    Sample Size n=(1.96/ Precision)^2 * p(1-p)

    Where n- minimum sample size required
    p- estimate of proportion of the of the population
    Precision – Level of precision desired from the sample in units of proportion
    1.96 – constant representing a 95% confidence interval

    So you consider it on your case, the required sample size would be 62 samples (61.4656)

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