FACDIVIDE procedure

Represents a factor by factorial combinations of a set of factors (R.W. Payne).

Option

OLDFACTOR = factor	Factor whose levels are to be represented by the factorial combinations of the NEWFACTORs

Parameters

NEWFACTOR = factors	Factors formed to represent OLDFACTOR
LEVELS = scalars or variates	Levels of the NEWFACTORs

Description

FACDIVIDE allows a set of factors to be formed with a set of levels for every level of another factor. (It is thus provides the opposite operation to the procedure FACPRODUCT, which forms a factor with a level for every combination of the levels of a set of factors.) FACDIVIDE may be useful, for example, if a design for a single factor, such as a Latin square, is to be used to study several factors and their interactions: e.g. a 12 by 12 Latin square could be used to study the main effects and interaction of factors A and B with 3 and 4 levels respectively.

The original factor is specified by the OLDFACTOR option, and the NEWFACTOR and LEVELS parameters specify the new factors and their levels. So, to represent the 12-level factor Treat by factors A and B as above, would require

FACDIVIDE [OLDFACTOR=Treat] NEWFACTOR=A,B; LEVELS=3,4

As in the FACTOR directive, the LEVELS parameter can be set to a scalar if the new factor is to have the standard levels 1, 2 and so on, or to a variate if you want to specify some other levels.

Options: OLDFACTOR. Parameters: NEWFACTOR, LEVELS.

Method

FACDIVIDE uses GENERATE to form a set of mapping vectors containing the levels of the new factors, in standard order. It then uses these in the NEWLEVELS function to calculate the levels of the new factors.

Action with RESTRICT

If any OLDFACTOR is restricted, the levels will be formed only for the units not excluded by the restriction.

See also

Procedures: AFUNITS, FACPRODUCT, FACCOMBINATIONS, FBASICCONTRASTS, FDISTINCTFACTORS.

Commands for: Calculations and manipulation, Design of experiments.

Example

CAPTION    'FACDIVIDE example'; STYLE=meta
FACTOR     [LEVELS=12; VALUES=2,10,5,6,11,3,8,1,9,4,12,7] Factor12
FACDIVIDE  [OLDFACTOR=Factor12] Factor3,Factor4; LEVELS=3,4
PRINT      Factor12,Factor3,Factor4
" sort the levels to see how they have been allocated "
SORT       Factor12,Factor3,Factor4
PRINT      Factor12,Factor3,Factor4