8
Chapter 2
Sampling Wizard: Sampling Method
Figure 2-3
Sampling Wizard, Sampling Method step
This step allows you to specify how to select cases from the active dataset.
Method. Controls in this groupare used to choose a selection method. Some sampling types allow
you to choose whether tosample with replacement (WR) or without replacement (WOR). See the
type descriptions for more information. Note that some probability-proportional-to-size (P PS)
types are available only when clusters have beendefined and that all PPS types are available only
inthe first stage of a design. Moreover,WR methods are available only in the last stage of a design.
SimpleRandom Sampling. Units are selected with equal probability. They can be selected
with or without replacement.
SimpleSystematic. Units are selected at a fixed interval throughout the sampling frame (or
strata, if they have been specified) and extractedwithout replacement. A randomly selected
unit within the first interval is chosen as the starting point.
Simple Sequential. Units are selected sequentially with equal probability and without
replacement.
PPS. This is a first-stage method that selectsunits at random with probability proportional
to size. Any units can be selected with replacement; only clusters can be sampled without
replacement.