Survey Software: R pps package
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Summary of survey software:
**R pps package**

The author, Jack
Gambino, provides the following description:

The pps package contains functions to select samples using PPS
(probability proportional to size) sampling. It also includes a function
for stratified simple random sampling, a function to compute joint
inclusion probabilities for Sampford's method of PPS sampling, and a few
utility functions.
You can get the package at the R site http://cran.r-project.org/ (The
direct URL is http://cran.r-project.org/src/contrib/Descriptions/pps.html)