Plots residuals from an `ANOVA`

analysis (R.W. Payne & A.D. Todd).

### Options

`RMETHOD` = string token |
Type of residuals to plot (`simple` , `standardized` ); default `simp` |
---|---|

`INDEX` = variate or factor |
X-variable for an index plot; default `!(1,2...)` |

`STRATUM` = formula |
The stratum (or error term) whose residuals are to be plotted; the default is to plot the residuals from the final stratum |

`GRAPHICS` = string token |
What type of graphics to use (`lineprinter` , `highresolution` ); default `high` |

`TITLE` = text |
Overall title for the plots; if unset, the identifier of the y-variate is used |

`SAVE` =
save structure |
Specifies the analysis from which the residuals and fitted values are to be taken; by default they are taken from the most recent `ANOVA` |

### Parameters

`METHOD` = string tokens |
Type of residual plot (`fittedvalues` , `normal` , `halfnormal` , `histogram` , `absresidual` , `index` ); default `fitt` , `norm` , `half` , `hist` |
---|---|

`PEN` = scalars, variates or factors |
Pen(s) to use for each plot |

### Description

Procedure `APLOT`

provides up to four types of plots of residuals from an `ANOVA`

analysis. These are selected using the `METHOD`

parameter, with settings: `fitted`

for residuals versus fitted values, `normal`

for a Normal plot, `halfnormal`

for a half-Normal plot, `histogram`

for a histogram of residuals, `absresidual`

for a plot of the absolute values of the residuals versus the fitted values, and `index`

for a plot against an “index” variable (specified by the `INDEX`

option). The `PEN`

parameter can specify the graphics pen or pens to use for each plot. The `TITLE`

option can supply an overall title. If this is not set, the identifier of the y-variate is used.

The residuals and fitted values are accessed automatically from the structure specified by the `SAVE`

option. If the `SAVE`

option is not set, they are taken from the `SAVE`

structure of the last y-variate to have been analysed by `ANOVA`

. By default, simple residuals are plotted, but you can set option `RMETHOD=standardized`

to plot standardized residuals instead.

If your design has several strata (or error terms), you can set the `STRATUM`

option to plot the residuals from one of the higher strata. If `STRATUM`

is not set, the residuals from the final stratum are plotted.

By default, high-resolution graphics are used. Line-printer graphics can be used by setting option `GRAPHICS=lineprinter`

.

Options: `RMETHOD`

, `INDEX`

, `STRATUM`

, `GRAPHICS`

, `TITLE`

, `SAVE`

.

Parameters: `METHOD`

, `PEN`

.

### Method

Residuals and fitted values are accessed, using `AKEEP`

, from the latest `ANOVA`

or from that specified by the `SAVE`

option. The plots are produced using the `DRESIDUALS`

procedure.

### Action with `RESTRICT`

If the y-variate in the `ANOVA`

was restricted, only the units not excluded by the restriction will be included in the graphs.

### See also

Directive: `ANOVA`

.

Procedures: `ACHECK`

, `AGRAPH`

, `AFIELDRESIDUALS`

, `RCHECK`

, `VPLOT`

.

Commands for: Analysis of variance.

### Example

CAPTION 'APLOT example 1',\ !t('Data from Snedecor & Cochran (1980), Statistical',\ 'Methods, (Iowa State University Press), page 305;',\ 'also see the Guide to Genstat, Part 2, Section 4.1.');\ STYLE=meta,plain FACTOR [LABELS=!T(beef,cereal,pork); VALUES=(1...3)20] Source & [LABELS=!T(high,low); VALUES=3(1,2)10] Amount VARIATE [NVALUES=60] Gain READ Gain 73 98 94 90 107 49 102 74 79 76 95 82 118 56 96 90 97 73 104 111 98 64 80 86 81 95 102 86 98 81 107 88 102 51 74 97 100 82 108 72 74 106 87 77 91 90 67 70 117 86 120 95 89 61 111 92 105 78 58 82 : BLOCKSTRUCTURE TREATMENTSTRUCTURE Source*Amount ANOVA [PRINT=aovtable] Gain APLOT fittedvalues, normal, halfnormal, histogram & [GRAPHICS=lineprinter] fittedvalues, normal, halfnormal, histogram CAPTION 'APLOT example 2',!t('Split plot design, see the',\ 'Guide to Genstat, Part 2, Section 4.2.1.'); STYLE=meta,plain FACTOR [NVALUES=72; LEVELS=6] Blocks & [LEVELS=3] Wplots & [LEVELS=4] Subplots GENERATE Blocks,Wplots,Subplots FACTOR [LABELS=!T('0 cwt','0.2 cwt','0.4 cwt','0.6 cwt')] Nitrogen & [LABELS=!T(Victory,'Golden rain',Marvellous)] Variety VARIATE Yield; DECIMALS=2; EXTRA=' of oats in cwt. per acre' READ [SERIAL=yes] Nitrogen,Variety,Yield 4 3 2 1 1 2 4 3 1 2 3 4 3 1 2 4 4 1 2 3 2 1 3 4 2 3 4 1 4 2 3 1 1 4 2 3 3 4 1 2 1 3 4 2 2 3 4 1 4 1 3 2 3 4 1 2 3 4 2 1 3 1 4 2 4 3 1 2 1 2 3 4 : 3 3 3 3 1 1 1 1 2 2 2 2 3 3 3 3 1 1 1 1 2 2 2 2 2 2 2 2 3 3 3 3 1 1 1 1 3 3 3 3 2 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 3 3 3 3 1 1 1 1 2 2 2 2 3 3 3 3 : 156 118 140 105 111 130 174 157 117 114 161 141 104 70 89 117 122 74 89 81 103 64 132 133 108 126 149 70 144 124 121 96 61 100 91 97 109 99 63 70 80 94 126 82 90 100 116 62 96 60 89 102 112 86 68 64 132 124 129 89 118 53 113 74 104 86 89 82 97 99 119 121 : " Convert yields to cwt per acre." CALCULATE Yield=(Yield*80)/(112*4) " Define the treatment structure: factorial effects of V and N." TREATMENTS Variety*Nitrogen " Subplots nested within whole-plots nested within blocks." BLOCK Blocks/Wplots/Subplots ANOVA [PRINT=means] Yield APLOT & [STRATUM=Blocks.Wplots] & [STRATUM=Blocks] APLOT [GRAPHICS=lineprinter] & [STRATUM=Blocks.Wplots] & [STRATUM=Blocks]