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APLOT procedure

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 = ANOVA 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]
Updated on March 8, 2019

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