|Controls what summary output is produced about the models (
||Controls the output from the
||Controls the output to present to present from the
||Model-definition structures specifying the models to try|
||Terms (fixed or random) for which effects or means are to be printed; default
||Standard errors to be printed with tables of effects and means (
||Whether to include units with missing values in the explanatory factors and variates and/or the y-variates (
||How to choose the best model (
||Whether to exclude models where any estimated variance parameters are held at a bound (
||Saves the number of the best model for each y-variate, returning a missing value if no models could be fitted successfully|
||Save structure from the analysis of the best model for each y-variate|
VARANDOM allows you to try several alternative random models for a
REML analysis, and then select the best one according to either their Akaike or Schwarz (Bayesian) information coefficients.
Model-definition structures for the models to be assessed must be specified using the
MODELSTRUCTURES option. These are formed using the
VFSTRUCTURE procedures, which define the aspects controlled by the
VSTRUCTURE directives, respectively.
The response variate for the analysis must be specified by the
Y parameter. The number of the best model can be saved, in a scalar, by the
NBESTMODEL parameter; it returns a missing value if no models could be fitted successfully The
REML save structure from the analysis with the best model can be saved using the
MVINCLUDE option controls whether units with missing values in the explanatory factors and variates and/or the y-variate are included in the analysis, as in the
METHOD option specifies how to assess the models
||uses their Akaike information coefficients,|
||uses their Schwarz (Bayesian) information coefficients (default).|
You can set option
bound, to excludes models with any estimated variance parameters held at a bound.
VRACCUMULATE procedure (which is used to store and then print details of the analyses). There is also an extra setting
best, which prints the description of the best model. The default is to print the best description, together with the deviance, the Akaike and Schwarz (Bayesian) information coefficients and the number of degrees, for all the random models.
PBEST option specifies the output to be produced from the
REML analysis with the best model. Similarly, the
PTRY option indicates what output should be produced for each candidate random model when it is tried. Their settings are mainly the same as those of the
REML directive. There are also extra settings
sic (with a synonym
bic) to print the Akaike and Schwarz (Bayesian) information coefficients, respectively. The default for both these options is to produce no output.
PTERMS option operates as in
REML, to specify the terms whose means and effects are printed by
PTRY; the default is all the fixed terms. Likewise, the
PSE option controls the type of standard error that is displayed with the means and effects; the default is to give a summary of the standard errors of differences.
Commands for: REML analysis of linear mixed models.
CAPTION 'VARANDOM example',\ 'Slate Hall Farm data (Guide to REML in Genstat, Section 1.8).';\ STYLE=meta,plain SPLOAD '%gendir%/data/slatehall.gsh' " define model for analysis as a randomized-blocks design " VFMODEL [MODELSTRUCTURE=RCBD; DESCRIPTION='Randomized blocks';\ FIXED=variety] replicates " define model for analysis as a Lattice square design " VFMODEL [MODELSTRUCTURE=Latticesq; DESCRIPTION='Lattice square';\ FIXED=variety] replicates/(rows*columns) " define model for analysis with an AR1 (x) AR1 model " VFMODEL [MODELSTRUCTURE=AR1xAR1; DESCRIPTION='AR1 (x) AR1';\ FIXED=variety] fieldrow.fieldcolumn VFSTRUCTURE [MODELSTRUCTURE=AR1xAR1; TERMS=fieldrow.fieldcolumn]\ 2('AR'); ORDER=1; FACTOR=fieldrow,fieldcolumn " define model for analysis with an AR1 (x) AR1 model + measurement error " VFMODEL [MODELSTRUCTURE=AR1xAR1p; DESCRIPTION='AR1 (x) AR1 + plots';\ FIXED=variety] fieldrow.fieldcolumn+plotnumber VFSTRUCTURE [MODELSTRUCTURE=AR1xAR1p; TERMS=fieldrow.fieldcolumn]\ 2('AR'); ORDER=1; FACTOR=fieldrow,fieldcolumn VARANDOM [MODELSTRUCTURES=RCBD,Latticesq,AR1xAR1,AR1xAR1p]\ yield; SAVE=savebest VDISPLAY [PRINT=model,components,wald] savebest