Significant net difference test
Quick reference
To request a significant net difference test, type:
tstat ntd [;options]
after the tab or l statement, and:
stat ntd, element_ids
in the axis at the point at which the results should be printed.
More information
This test deals with each row independently and compares the proportions in four columns at a time to test whether the difference between the values in the first pair of columns is significantly different from the difference between the values in the second pair of columns. For example, when comparing columns A, B, C and D, the difference between A and B is tested against the difference between C and D to see whether the difference between the two is significant.
To request a significant net difference test
1 Insert the statement tstat ntd under the tab or l statement which creates the table or axis to be tested.
Columns to be tested must be defined in groups of exactly four. For example:
stat ntd;elms=ABCD,EFGH
If the number of sets of letters does not match the number of stat ntd statements in the axis, the excess of either type is ignored and a warning message to this effect is issued. Therefore, if there are three groups of columns defined with tstat but only two stat ntd elements in the axis, only two statistics are calculated.
2 For each group of columns to be tested, place a stat ntd statement in the column axis to determine where the results for those columns should be printed.
The
stat ntd statement has the same format as the statements described in
Descriptive statistics and
Z, T and F tests.
3 Optionally, add decp= with a value greater than 0 to the row elements of the table being tested. (decp= at any higher level has no effect on the way Quantum prints this statistic.)
The number of decimal places shown for the T statistic is controlled by decp=, for which the default is zero. If the value of the T statistic is less than one you could find that the T statistic is replaced by the spechar characters. Setting the number of decimal places to one or more prevents this happening.
See
See also