Generates fractional factorial designs (M.F. Franklin & R.W. Payne).
|Controls whether or not to print a plan of the design (
||Controls whether or not to analyse the design, and produce a skeleton analysis-of-variance table using
||Limit on number of factors in treatments terms in the analysis of variance; default 2|
||Name of the backing store file containing the design information; default uses the standard fractional design file|
||Number of levels of the treatment factors in each design|
||Denominator of required fraction|
||Number of treatment factors|
||Number of units per block|
||Seed to be used to randomize each design; a negative value implies no randomization|
||Specifies identifiers for the treatment factors|
||Identifier for the block factor|
||Identifier for the factor to index the units (or plots) within each block|
||Saves a command to recreate each design (useful if the design information has been specified in response to questions from
AGFRACTION generates fractional factorial designs from stored keys & other information. It also sets the block and treatment formulae (using the
TREATMENTSTRUCTURE directives) to allow the design to be analysed by
The procedure relies upon a backing-store file that contains a repertoire of available designs, together with the information required to form them. There is a standard file, used by default, but the
FILENAME option allows you to specify another if you wish to form your own alternative file.
AGFRACTION has two other options. The
design to print the plan of the design. By default, if you are running Genstat in batch, the plan is not printed. If you do not set
AGFRACTION will ask whether or not you wish to print the design. Similarly the
ANALYSE option governs whether or not
AGFRACTION produces a skeleton analysis-of-variance table (containing just source of variation, degrees of freedom and efficiency factors). Again
AGFRACTION assumes that this is not required if
ANALYSE is unset in a batch run, and asks whether it is required if
ANALYSE is unset in an interactive run. The
FACTORIAL option sets a limit on the number of factors in the treatment terms in the analysis of variance; by default, this is two.
The information required to select the design and give identifiers to its factors can be defined using the parameters of
AGFRACTION. In an interactive run,
AGFRACTION will ask questions to obtain any necessary information that is not supplied in this way; when running in batch, if any of the required information has not been specified,
AGFRACTION will terminate with a warning message.
It is thus easiest to use
AGFRACTION interactively. Then all the information necessary to select and define the required design will be obtained by (clearly explained) questions. You need set the parameters only if you wish to anticipate some of the questions, or if you wish to use
AGFRACTION in batch. If, however, you wish to recreate the same design later, the
STATEMENT parameter allows you to save a Genstat text structure containing a command specifying the same information.
The number of levels of the treatment factors can be defined using the
LEVELS parameter. The
FRACTION parameter defines the denominator of the required fraction, and the
NTREATMENTFACTOR parameter specifies how many treatment factors the design is to contain. Thus, for example,
AGFRACTION [PRINT=design] LEVELS=2; FRACTION=4; NTREATMENTF=6
would print the plan of a quarter replicate of a 26 design.
For some of the designs it is possible also to allow a blocking factor (and you will be given details of what is feasible if you are running
AGFRACTION interactively). The
NUNITS parameter can then be used to define the number of units per block.
SEED parameter allows you to specify a seed to be used to randomize the design. In batch the default seed is -1, to suppress randomization. If you do not set
SEED when running interactively
AGFRACTION will ask for a seed, and again a negative value suppresses any randomization.
TREATMENTFACTORS parameter can specify a pointer to supply identifiers for the treatment factors in the design. For example, if there are two factors you could define their identifiers to be
B by forming the pointer
Tf (say) with the statement
POINTER [VALUES=A,B] Tf
and then setting
TREATMENTFACTORS=Tf. Alternatively, and more succinctly, you could put
!p(A,B) is an unnamed pointer containing the required two identifiers. The remaining parameters,
UNITS, allow you to specify identifiers for the block and unit-within-block factors. If the treatment, block or unit factors are not specified in a batch run,
AGFRACTION will use identifiers that are local within the procedure and thus lost at the end of the procedure. If you are running interactively,
AGFRACTION will ask you to provide identifiers, and these will remain available after
AGFRACTION has finished running.
CAPTION 'AGFRACTION example',!t(\ 'This example prints the (unrandomized) plan',\ 'of a quarter replicate of a 2x2x2x2x2x2.'); STYLE=meta,plain AGFRACTION [PRINT=design; ANALYSE=no] LEVELS=2; FRACTION=4;\ NTREATMENTFACTORS=6; NUNITS=16; TREATMENTFACTORS=!p(A,B,C,D,E,F);\ SEED=-1 " To see the full repertoire of designs, you should run AGFRACTION interactively, without setting the parameters."