**QTAB Significance Testing Library **

QTAB's post processing provides a flexible means for manipulating and formatting table rows, columns and individual cells after tabulation.

This example uses a library of post processing instructions that may be used to perform significance testing between any pairs of columns. Proportions are tested using z-scores and means are tested using t-tests. Both one-way (A is compared to B and A is flagged) and two-way (A and B are compared and the cell with the larger frequency is flagged) tests are provided.

The library consists of 5 QTAB spec files. SIGTEST1.QTS provides critical test values used to determine significance levels and the basic post processing instructions to compute the z-scores and t-tests. It passes these to STXZ1PP1.QTS, STXZ2PP1.QTS, STXT1PP1.QTS and STXT2PP1.QTS which apply those instructions to all possible combinations of columns. SIGTEST1.QTS also contains extensive comments describing what each post processing set does and how to use the library. Only the instructions in SIGTEST1.QTS need to be modified in order to change the test formulas.

The entire significance testing library is called from a QTAB spec file by a single

statement as shown in the sample spec file QT32DST1.QTS.
**#INCLUDE**

QT32DST1.ZIP contains the QTAB significance testing library, sample spec, data and output files.