Finds out information about aliased model terms in analysis of variance (R.W. Payne).

### Options

`TREATMENTSTRUCTURE` = formula |
Treatment model for the design |
---|---|

`BLOCKSTRUCTURE` = formula |
Block model for the design |

`FACTORIAL` = scalar |
Value used in the `FACTORIAL` option of `ANOVA` if not the default |

`DESIGN` = pointer |
Design structure for the analysis |

### Parameter

`TERM` = factors |
Factors defining the aliased model term |
---|

### Description

When a term is aliased in an analysis of variance, it is listed in the Information summary (produced by `ANOVA [PRINT=information]`

) under the heading “Aliased model terms” (see the *Guide to the Genstat Command Language*, Part 2, Section 4.7.1). However `ANOVA`

does not indicate the terms with which it is aliased. This information can be obtained using procedure `ALIAS`

.

The aliased term is specified by setting the `TERM`

parameter to the list of factors that define it. The structure of the design can be specified either by options `BLOCKSTRUCTURE`

and `TREATMENTSTRUCTURE`

(together with option `FACTORIAL`

, if necessary); alternatively you can save the design structure from the original analysis and supply this using the `DESIGN`

option – this is the only way of specifying the design if there are weights or if the analysis is restricted. If an undeclared structure is specified for `DESIGN`

(and `BLOCKSTRUCTURE`

and `TREATMENTSTRUCTURE`

are also specified), it will be set to the design structure for the analysis.

**Note**: this procedure has been replaced by FALIASTERMS, but is retained for use in earlier programs. FALIASTERMS has a more convenient syntax, and allows you to save details of the aliased terms.

Options: `TREATMENTSTRUCTURE`

, `BLOCKSTRUCTURE`

, `FACTORIAL`

, `DESIGN`

.

Parameter: `TERM`

.

### Method

The procedure calculates a set of dummy effects for the aliased model term, and then forms and analyses a variate in which only these effects are present. The analysis detects the model terms to which the term is aliased as those that have non-zero sums of squares.

### Action with `RESTRICT`

None of the options nor parameters are vectors. To indicate that the analysis is of a restricted set of units you must use the `DESIGN`

option to specify the design structure from the original analysis.

### See also

Directives: `ANOVA`

, `FPSEUDOFACTORS`

.

Procedure: `AEFFICIENCY`

, `FALIASTERMS`

.

Commands for: Analysis of variance, Design of experiments.

### Example

CAPTION 'ALIAS example'; STYLE=meta FACTOR [NVALUES=32; LEVEL=2] A,B,C & [LEVEL=4] D,Blocks & [LEVEL=8] Plots GENERATE A,B,C & D & Blocks,Plots VARIATE [VALUES=13,17,25,33,18,19,22,14,26,23,31,29,25,21,18,34,\ 23,19,33,36,25,23,29,18,31,30,37,33,29,27,20,36] Y BLOCKSTRUCTURE Blocks/Plots TREATMENTSTRUCTURE A*B*C+D ANOVA [PRINT=aovtable,information] Y CAPTION !T('The aov table and information summary show that D is aliased;',\ 'ALIAS indicates that the aliasing is with B, C and B.C ') ALIAS [BLOCKSTRUCTURE=Blocks/Plots; TREATMENTSTRUCTURE=A*B*C+D] D PRINT !T('The printout below confirms this:',\ 'D level 1 corresponds to B level 1 and C level 1,',\ 'D level 2 corresponds to B level 1 and C level 2,',\ 'D level 3 corresponds to B level 2 and C level 1,',\ 'D level 4 corresponds to B level 2 and C level 2.');\ JUSTIFICATION=left & [RLWIDTH=3; ORIENTATION=across] D,B,C; FIELDWIDTH=2; JUST=left PRINT !T('Use RESTRICT to analyse only the first 3 blocks;',\ 'the main effect D is still aliased, exactly as before...');\ JUSTIFICATION=left RESTRICT Y; Blocks < 4 ANOVA [PRINT=aovtable,information; DESIGN=DB1to3] Y CAPTION 'The design must now be specified for ALIAS using the DESIGN option.' ALIAS [DESIGN=DB1to3] D