PASS

A common task in research is to compare the averages of two or more populations (groups). We might want to compare the income level of two regions, the nitrogen content of three lakes, or the effectiveness of four drugs. The one-way analysis of variance compares the means of two or more groups to determine if at least one mean is different from the others. The F test is used to determine statistical significance.

Analysis of Covariance (ANCOVA) is an extension of the one-way analysis of variance model that adds quantitative variables (covariates). When used, it is assumed that their inclusion will reduce the size of the error variance and thus increase the power of the design.

In this procedure, covariates can only be used if the assumption of parallel slopes is viable.

The new ANCOVA procedure computes power and sample size for comparing means when equal-slope covariates are included.

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).