PASS

This procedure computes power and sample size for tests of ordered categorical data such as Likert scale data. Assuming proportional odds, such data can be analyzed directly with a z-test, or using logistic regression or the Mann-Whitney test. The results used here were presented in a paper by Whitehead (1993). They are also mentioned in the book by Julious (2010) and Machin et al (1997).

Ordered categorical data often results from surveys such as a quality of life (QoL) survey in which responses are categories such as very good, good, moderate, poor. When there are only two categories, an analysis using two proportions should be used. When there are more than two responses, and those responses can be ordered, the techniques described in the documentation of this procedure can be used.

Minimum System Requirements
Click on one of the links below to view the minimum system requirements for NCSS and PASS products:
NCSS 8
PASS 11
PASS 2008
NCSS 2007
Previous Versions

Accuracy
We at NCSS have put a great deal of effort into finding the most accurate algorithms possible. The programs have been tested and verified over and over, both by us and by our customers. Each routine has been verified against textbooks, journal articles, and, where possible, other software. NCSS and PASS are some of the most accurate statistical analysis programs available. NCSS and PASS calculate with seventeen-digit, double-precision accuracy.

Guarantee
If you are not completely satisfied with an NCSS product during the first 30 days for any reason, return the program for a full, prompt refund (excluding shipping).