Wheat.dat

<p>The data appears in Gilmour et al. (1995) and is from a field experiment designed to compare the
performance of 25 varieties of spring wheat. An analysis of it using asreml is presented by 
Butler et al. (2023, Section 7.6), although they suggest that it is a barley experiment. 
It is used in the Wheat vignettes  [Enter <code>vignette(package = "asremlPlus")</code>] as an 
executable example of the use of the <code>asremlPlus</code> to analyse a data set.</p>
<p>The experiment was conducted at Slate Hall Farm, UK, in 1976 and was designed as 
a balanced lattice square with 6 replicates laid out in a 10 \(\times\) 15 rectangular
grid. The columns in the data frame are: Rep, Row, Column, WithinColPairs, Variety, yield.
The response variable is the grain yield.</p>

datasets

Assists in automating the selection of terms to include in mixed models when
'asreml' is used to fit the models. Procedures are available for choosing models that
conform to the hierarchy or marginality principle, for fitting and choosing between
two-dimensional spatial models using correlation, natural cubic smoothing spline and
P-spline models. A history of the fitting of a sequence of models is kept in a data frame.
Also used to compute functions and contrasts of, to investigate differences between and
to plot predictions obtained using any model fitting function. The content  falls into
the following natural groupings: (i) Data, (ii) Model modification functions, (iii) Model
selection and description functions, (iv) Model diagnostics and simulation functions,
(v) Prediction production and presentation functions, (vi) Response transformation
functions, (vii) Object manipulation functions, and (viii) Miscellaneous functions
(for further details see 'asremlPlus-package' in help). The 'asreml' package provides a
computationally efficient algorithm for fitting a wide range of linear mixed models using
Residual Maximum Likelihood. It is a commercial package and a license for it can be
purchased from 'VSNi' <https://vsni.co.uk/> as 'asreml-R', who will supply a zip file
for local installation/updating (see <https://asreml.kb.vsni.co.uk/>). It is not needed
for functions that are methods for 'alldiffs'  and 'data.frame' objects. The package
'asremPlus' can also be installed from <http://chris.brien.name/rpackages/>.

Wheat.dat: Data for a 1976 experiment to investigate 25 varieties of wheat

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