Primary Sampling Units (PSUs)
When you have clusters, or primary sampling units
(PSUs), in your sample design, the procedure estimates
variance from the variation among PSUs.
For more information, see
the section "Variance Estimation". You can use the CLUSTER statement to
identify the first stage clusters in your design. PROC
SURVEYREG assumes that each cluster represents a PSU
in the sample and that each observation is an element of
a PSU. If you do not specify a CLUSTER statement, the
procedure treats each observation as a PSU.
Copyright © 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.
