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Thread: Sample Size comparison

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    Sample Size comparison




    I am trying to, in Excel, compare two samples of the same material that are different sizes to compare the relative defect rate. Can anyone help me set that up?

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    Re: Sample Size comparison

    You want to use a 2 - Proportions test. Excel does not have this test in their Analysis add-in, but the formulas are fairly simple to replicate in Excel. See the Normal approximation test or Fisher's exact test for reference.

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    Thumbs up Re: Sample Size comparison

    Thank you very much

    Quote Originally Posted by Miner View Post
    You want to use a 2 - Proportions test. Excel does not have this test in their Analysis add-in, but the formulas are fairly simple to replicate in Excel. See the Normal approximation test or Fisher's exact test for reference.

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    Re: Sample Size comparison

    I tried using the formulas you suggested and I have a feeling I did not clearly describe what I am trying to accomplish. Two independent groups tested their own sample size (based on their group's sampling rules) of the same data for process failures. Group 1 has substantially larger sample size than Group 2; almost 20 times in size. Both groups then calculate the defect rate (findings/sample size) of the found failures; both defect rates because of the sample sizes are different and I need to find a way to show if the defect rates would be the same if the sample sizes were the same

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    Re: Sample Size comparison


    The difference in sample size will affect the width of the confidence interval around each estimate, but should not affect the estimate itself. The methods that I referenced take the different sample sizes into consideration.

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