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Math Help - Random sample and confidence intervals

  1. #1
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    Random sample and confidence intervals

    Company has n=5,000,000 customers that are using service X. We need to determine customer satisfaction with service X through phone survey.

    Is there a formal way to determine optimal sample size (assuming that all calls will be answered)?
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  2. #2
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    What confidence and error width do you deisre in the sample size?
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  3. #3
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    95% confidence, i don't know what error width is. (you can choose any appropriate error, I'm interested in approach, not just result for this specific case)
    Last edited by losm1; July 8th 2010 at 12:07 PM.
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  4. #4
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    It's good you have identified the confidence level required. The error width will be how far either side of this you can allow for.

    95\% \pm 3\% will require more samples than 95\% \pm 5\%

    Have a read of this guy.

    PEOD6/PD006: Determining Sample Size

    There is a table at the bottom that will give you some numbers to consider.
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