About conditional sampling

Conditional sampling is used to restrict sample selection to records that meet a specified condition. For example, transactions originating at a specified location or products made by a specified manufacturer. When you perform conditional sampling, you must ensure that you are working with an accurate data set. Because using a local filter to refine your data can yield unexpected results when sampling, a best practice is to extract the data that meets the desired condition to a new table and then perform your sampling on that table.

Note

Applying local filtering or scope parameters to data samples compromises the validity of your sample. If you do this, a note stating that the sample results may be invalid is generated in the log. Although the capability to apply local filters and scope parameters exists in the Sampling dialog box, the steps have been removed from the sampling procedures in this guide.

When performing conditional sampling, be aware of the difference between sampling filtered data versus filtering sampled data. For example, consider that you have a table that contains 1000 records and 150 of those records meet the condition of “Dept 03”. If you want to draw a sample of 10 records that have the condition of “Dept 03”, you must filter or extract your data before drawing your sample so that you are drawing only from records with “Dept 03”. If you use unfiltered data and then apply the local filter of IF Dept = "03", ACL selects 10 records from the unfiltered data set and then presents only the records that match the “Dept 03” condition, resulting in fewer than the required 10 records in the sample. For similar reasons, filtering a results output table containing sampled records invalidates the sample.

Related tasks
Sampling transaction records
Sampling monetary unit records


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