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  2. VFIXEDTESTS procedure


Saves fixed tests from a REML analysis (R.W. Payne).


FIXEDTESTS = pointer Saves the fixed tests
FMETHOD = string token Controls whether and how to calculate F-statistics (automatic, none, algebraic, numerical); default auto
WMETHOD = string token Controls which tests are saved (add, drop); default drop
SAVE = REML save structure Specifies the save structure from the required analysis; default * i.e. most recent one

No parameters


VFIXEDTESTS saves the results of the fixed tests in a REML analysis. By default the results are from the most recent REML, but you use the SAVE option to specify the save structure from some other analysis.

The WMETHOD option controls whether the tests are from the table where terms are added sequentially to the model, or that where terms are dropped from the full fixed model.

The FMETHOD option specifies which algorithm to use to calculate the denominator numbers of degrees of freedom required for F tests. The default, automatic, will use any stored values that have been calculated for this analysis by earlier REML, VDISPLAY or VKEEP statements; otherwise it will choose automatically between the two available methods. (See REML for more details.)

The tests are saved, in a pointer, using the FIXEDTESTS option. The pointer is labelled by the headings from the tests for fixed tests that appear in the REML output. If the denominator degrees of freedom are available, the labels and their corresponding vectors are as follows:

Term text containing the names of the fixed terms,
Wald statistic variate containing the Wald statistics,
n.d.f. variate containing the numerator degrees of freedom,
F statistic variate containing the F statistics,
d.d.f. variate containing the denominator degrees of freedom,
F pr. variate containing the probabilities for the F tests.

If the denominator degrees of freedom are not available (either because they could not be calculated, or because FMETHOD has been set to none), the labels F statistic, d.d.f. and F pr. are omitted, and instead there is

Chi pr. variate containing the probabilities for chi-square tests for the Wald statistics.

The vectors have an element for each fixed term, with missing values if its test results are unavailable. (For example, with the fixed model A*B, tests for the main effects A and B would be available only when WMETHOD=add.)

Parameters: none.

See also

Directive: VKEEP.
Commands for: REML analysis of linear mixed models.


CAPTION 'VFIXEDTESTS example','Guide Part 2, Example 5.3.6a'; STYLE=meta,plain
&       [LEVELS=18] Pup
FACTOR  [LEVELS=3; LABELS=!T('C','Low','High')] Dose
VARIATE [NVALUES=322] Littersize,Weight
OPEN    '%GENDIR%/Examples/GuidePart2/Rats.dat'; CHANNEL=inchan
READ    [CHANNEL=inchan] Dose,Sex,Littersize,Dam,Pup,Weight; \
CLOSE   inchan
VCOMPONENTS [FIXED=Littersize+Dose*Sex] RANDOM=Dam/Pup
REML        Weight
PRINT       Droptests[]
PRINT       Addtests[]
Updated on September 12, 2019

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