Sampling of Existing Documentation, Forms, and Files

• Document and File Sampling Techniques

  • Selecting the Sample:
    • Two commonly used sampling techniques are randomization and stratification.
      • Randomization is a sampling technique characterized as having no predetermined pattern or plan for selecting sample data.
        • Therefore, we just randomly choose 25 invoices.
      • Stratification is a systematic sampling technique that attempts to reduce the variance of the estimates by spreading out the sampling -- for example, choosing documents or records by formula -- and by avoiding very high or low estimates.
        • For computerized files, stratification sampling can be executed by writing a sample program.

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For computerized files, stratification sampling can be executed by writing a sample program. For instance, suppose our invoices were on a computer file that had a volume of approximately 250,000 invoices. Recall that our sample size needs to include 25 invoices. We will simply write a program that prints every 10,000th record (=250,000/25). For manual files and documents, we could execute a similar scheme.