138
Chapter 13
Figure 13-47
Data Editor with sample results
Unlike voters in the second stage, the first-stage sampling weights are not identical for townships
within the same countyb ecausethey are selected with probability proportional to size.
Figure 13-48
Joint probabilities file
The file poll_jointprob.sav contains first-stage joint probabilities for selectedtownships within
counties. County is a first-stage stratification variable, and Town ship is a cluster variable.
Combinations of these variables identifyall first-stage PSUs uniquely. Unit_No_ labels PSUs
within each stratum andis used to match up with Joint_ Prob_1_,Joint_Prob_2_,Joint_Prob_3_,
Joint_Prob_4_,andJoint_Prob_5_.Thefirsttwo strata each have 4 PSUs; therefore, the joint