user manual

138
Chapter 13
Figure 13-47
Dat a E dito r with sample results
Unlike voters in the second stage, the first-stage sampling weights are not identical for townships
within the same county because they are selected with probability proportional to size.
Figure 13-48
Joint probabilities file
The fi le poll_jointprob.sav contains first-stage joint probabilities for selected townships within
counties. County is a first-stage stratification variable, and Tow nship is a cluster variable.
Combinations of these v ariables identify all first-stage PSUs uniquely. Unit_No_ labels PSUs
within each stratum and is used to match up with Joint_Prob_1_, Joint_Prob_2_, Joint_Prob_3_,
Joint_Prob_4_,andJoint_Prob_5_.Thefirst two strata each have 4 PSUs; therefore, the joint