AFIELDRESIDUALS procedure
Display residuals in field layout (R.W. Payne & A.D.Todd).
Options
Parameters
Description
In a field experiment it can be useful to study the spatial pattern of the residuals, for example to see if there are any systematic trends in fertility.
The locations of the plots are defined by the Y and X parameters, specifying variates or factors containing their y- and x-coordinates respectively. By default the residuals are taken from the most recent ANOVA analysis. You can take the residuals from some other analysis, by specifying its save structure using the SAVE parameter. This can be from another ANOVA analysis, a REML analysis or a regression analysis (see MODEL).
The METHOD option determines the type of residuals that are taken. The default setting combined gives residuals combining the residuals from all the strata or error terms in the analysis. These corresponds to the CBRESIDUALS option of the AKEEP directive, or the use of the RESIDUALS option in VKEEP with option RMETHOD=all. Regression allows only a single error term, so combined is treated as the same as the next setting, finalstratum.
The setting finalstratum uses simple residuals from the final stratum or error term. These correspond to the RESIDUALS option of AKEEP with option RMETHOD=simple, or the RESIDUALS option of VKEEP with option RMETHOD=final, or the RESIDUALS parameter of RKEEP with option RMETHOD=simple.
The last setting, standardizedfinal, uses standardized residuals from the final stratum or error term. These correspond to the RESIDUALS option of AKEEP with option RMETHOD=standardized, or the RESIDUALS parameter of RKEEP with option RMETHOD=deviance. They are not available from REML analyses.
Usually, the plots will all have different coordinates. However, if there are several plots with the same coordinates, mean residuals are calculated for each location. Thus for example, if you wanted only to look at the block and whole-plot residuals in a split-plot design, you could request combined residuals and then set identical coordinates for the (sub-) plots within each whole plot.
AFIELDRESIDUALS provides three forms of representation, selected using the PRINT option as follows:
The GRAPHICS option determines the type of graphics that is used, with settings highresolution (the default) and lineprinter. No graph can be produced if the plots are in an irregular 2-dimensional arrangement. High-resolution contour plots require more than 3 rows and columns, and line-printer contour plots require more than 4 rows and columns. The way in which the lines are drawn in high-resolution contour plots is defined by the properties of the pen specified by the PENCONTOUR option, while the pen specified by the PENFILL parameter defines how to shade the areas between the contours. Their defaults are 1 and 3 respectively. Similarly, the pen or pens specified by the PENSHADE option control the colouring of the shade plot; the default is to use pen 3. For more information see the DCONTOUR and DSHADE directives.
The MARGIN option, with settings no (default) and yes, determines whether or not marginal summaries are included with the printed tables. The FIELDWIDTH and DECIMALS parameters can be used to specify the formats of the printed tables (as in the PRINT directive). The TITLE parameter can supply a title for the plots. If this is unset, a default title is formed.
Options: PRINT, GRAPHICS, METHOD, MARGIN, PENCONTOUR, PENFILL, PENSHADE.
Parameters: Y, X, RESIDUALS, SAVE, FIELDWIDTH, DECIMALS, TITLE.
Method
AFIELDRESIDUALS obtains the residuals using the AKEEP, VKEEP or RKEEP directives, and then uses the standard GenStat facilities for manipulation and plotting.
Action with
RESTRICT
If any of X, Y or RESIDUALS is restricted, only the unrestricted plots are displayed.