Defines options for the fitting of models by `VARANDOM`

and associated procedures (R.W. Payne).

### Options

`MAXCYCLE` = scalar |
Limit on the number of iterations in `REML` analyses; default 100 |
---|---|

`WORKSPACE` = scalar |
Number of blocks of internal memory to be set up for use by the `REML` algorithm |

`MINSPATIALCOORDINATES` = scalar |
Minimum number of different coordinates in a direction for a spatial model to be fitted by `VAROWCOLUMNDESIGN` ; default 4 |

`LIMPRTREND` = scalar |
Critical value for the probability of a row or column trend in the initial basic `REML` analysis (with replicates but no other random terms) for this to be included in the later analyses) by `VAROWCOLUMNDESIGN` ; default 0.01 |

`REPORTFAILURES` = string token |
Whether the accumulated summary should include models that fail to fit or that have bound variance parameters (`yes` , `no` ) ; default `no` |

### No parameters

### Description

There are several procedures, with the prefix `VA`

, that investigate potential models for a `REML`

analysis. For example, `VABLOCKDESIGN`

does this for data from an incomplete-block design, and `VAROWCOLUMNDESIGN`

does it for data from a field trial arranged in rows and columns. These two procedures both use a general procedure `VARANDOM`

, which 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.

`VABLOCKDESIGN`

and `VAROWCOLUMNDESIGN`

are designed to be used by non-expert users, and so various decisions are made there (and in `VARANDOM`

) about how the analysis is to be done and how the models are to be selected. This procedure, `VAOPTIONS`

, is provided to allow more experienced users to modify some of the options that control the process.

The `MAXCYCLE`

and `WORKSPACE`

options are relevant to all the procedures, and define the settings for the `MAXCYCLE`

and `WORKSPACE`

options of the `REML`

directive, when this is used in any of the procedures.

Other options are relevant to specific procedures. The `MINSPATIALCOORDINATES`

and `LIMPRTREND`

options control aspects of the analyses in `VAROWCOLUMNDESIGN`

. `MINSPATIALCOORDINATES`

sets a limit on the number of different row or column coordinates for a spatial model to be fitted in that direction (default 4). `LIMPRTREND`

defines the critical value for the probability of a row or column trend in an initial basic `REML`

analysis, that is performed with replicates but no other random terms, to decide whether this is be included in the later analyses (default 0.01). The `REPORTFAILURES`

option controls whether the accumulated summary, printed from `VARANDOM`

, should include models that fail to fit or that have bound variance parameters.

Options: `MAXCYCLE`

, `WORKSPACE`

, `MINSPATIALCOORDINATES`

, `LIMPRTREND`

, `REPORTFAILURES`

.

Parameters: none.

### See also

Directive: `REML`

.

Procedures: `VABLOCKDESIGN`

, `VAROWCOLUMNDESIGN`

, `VARANDOM`

.

Commands for: REML analysis of linear mixed models.

### Example

CAPTION 'VAOPTIONS 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 " find the best random model " VARANDOM [PTRY=monitor; MODELSTRUCTURES=RCBD,Latticesq,AR1xAR1,AR1xAR1p]\ yield; SAVE=savebest " set MAXCYCLE=8 in future REMLs (the spatial analyses will now fail) " VAOPTIONS [MAXCYCLE=8] VARANDOM [PTRY=monitor; MODELSTRUCTURES=RCBD,Latticesq,AR1xAR1,AR1xAR1p]\ yield; SAVE=savebest " restore MAXCYCLE to the default 100 " VAOPTIONS [MAXCYCLE=100]