Using the Wizard

  1. To run the Complex Samples Sampling Wizard, from the menus choose:

    Analyze > Complex Samples > Select a Sample...

    Figure 1. Sampling Wizard, Welcome step
    The Complex Samples Sampling Wizard Welcome Step.
  2. In the Welcome step, select Design a sample, browse to where you want to save the file, and type poll.csplan as the name of the plan file.
  3. Click Next.
    Figure 2. Sampling Wizard, Design Variables step (stage 1)
    The Complex Samples Sampling Wizard Design Variables Step.
  4. In the Design Variables step, select County as a stratification variable.
  5. Select Township as a cluster variable.
  6. Click Next.

    This design structure means that independent samples are drawn for each county. In this stage, townships are drawn as the primary sampling unit.

    Figure 3. Sampling Wizard, Sampling Method step (stage 1)
    The Complex Samples Sampling Wizard Method Step.
  7. In the Sampling Method step, select PPS as the sampling method.
  8. Select Count data records as the measure of size.
  9. Click Next.

    Within each county, townships are drawn without replacement with probability proportional to the number of records for each township. Using a PPS method generates joint sampling probabilities for the townships; you will specify where to save these values in the Output Files step.

    Figure 4. Sampling Wizard, Sample Size step (stage 1)
    The Complex Samples Sampling Wizard Sample Size Step.
  10. In the Sample Size step, select Proportions from the Units drop-down list.
  11. Type 0.3 in the Value field. This is the proportion of townships to select per county in this stage.

    Legislators from the Western county point out that there are fewer townships in their county than in others. In order to ensure adequate representation, they would like to establish a minimum of 3 townships sampled from each county.

  12. Type 3 in the Minimum Count field and 5 in the Maximum Count field.
  13. Click Next, and then click Next in the Output Variables step.
    Figure 5. Sampling Wizard, Plan Summary step (stage 1)
    The Complex Samples Sampling Wizard Stage Summary Step
  14. In the Plan Summary step, select Yes, add stage 2 now.
  15. Click Next.
    Figure 6. Sampling Wizard, Design Variables step (stage 2)
    The Complex Samples Sampling Wizard Design Variables Step
  16. In the Design Variables step for stage 2, select Neighborhood as a stratification variable.
  17. Click Next, and then click Next in the Sampling Method step.

    This design structure means that independent samples are drawn for each neighborhood of the townships drawn in stage 1. In this stage, voters are drawn as the primary sampling unit using simple random sampling without replacement.

    Figure 7. Sampling Wizard, Sample Size step (stage 2)
    The Complex Samples Sampling Wizard Sample Size step.
  18. In the Sample Size step for stage 2, select Proportions from the Units drop-down list.
  19. Type 0.2 in the Value field. This is the proportion of units to sample from each strata.
  20. Click Next, and then click Next in the Output Variables step.
  21. Click Next in the Plan Summary step.
    Figure 8. Sampling Wizard, Draw Sample Selection Options step
    The Complex Samples Sampling Wizard Draw Sample: Selection Options Step
  22. In the Draw Sample Selection Options step, select Custom value for the type of random seed to use, and type 592004 as the value.

    Using a custom value allows you to replicate the results of this example exactly.

  23. Click Next.
    Figure 9. Sampling Wizard, Draw Sample Selection Options step
    The Complex Samples Sampling Wizard Draw Sample: Output Files Step
  24. In the Draw Sample Output Files step, choose to save the sample to a new dataset, and type poll_cs_sample as the name of the dataset.
  25. Browse to where you want to save the joint probabilities and type poll_jointprob.sav as the name of the joint probabilities file.
  26. Click Next.
    Figure 10. Sampling Wizard, Finish step
    The Complex Samples Sampling Wizard Finish Step
  27. Click Finish.

These selections produce the sampling plan file poll.csplan and draw a sample according to that plan, save the sample results to the new dataset poll_cs_sample, and save the joint probabilities file to the external data file poll_jointprob.sav.

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