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Sample Size for Survey

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  • October 1, 2008 at 3:13 pm #51048

    JM
    ★ 10 Years ★
    Participant

    The company I work for measures customer satisfaction (CS) through survey. However, we publish a monthly performance report. Because CS is through survey, the monthly number is not stable, i.e., the reported number changes almost every month, which is becoming a concern, we receive returns after 3-4 months sometimes after 6 months. But they want to see a monthly result. The company has 900 K customers and sends out 1500 survey every month. How much of the survey return should we wait for, for the result to be significant? or any suggestion on this process.
    Thanks,
    JM

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    October 1, 2008 at 4:31 pm #176339

    GB
    ★ 10 Years ★
    Participant

    95% CL/5% CI =384

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    October 2, 2008 at 2:47 pm #176375

    fevila
    ★ 10 Years ★
    Participant

    Hi JM,
    The validity of answers will also depend on the type of survey you are sending out.
    If it is a transactional survey, i.e. related to a transaction like a purchase, initial use of a product or a support activity (like a repair or question to a call center), then you should consider only responses sent at most 10 or 15 days after the transaction date. After this time details of the transaction begin to fade and results are not as valuable. This means that responses coming a month or 2 later should not be used at all.
    However if it is a relationship survey, i.e. related at how your customer feels about the relationship with your company, you don’t have this time limit and practicality/timing of reporting should guide your time limits.
    You should be sending out enough surveys that normal response rate whithin a reasonable time frame give you adequate statistical significance. This way you can disregard any late answers from your metric.
    Whatever you do, has to be consistent month after month.

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    October 3, 2008 at 9:31 am #176391

    Van Loon
    ★ 10 Years ★
    Participant

    What is the power of this test ?
    Jan

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