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ASReml-S reference manual - VSN International

ASReml-S reference manual - VSN International

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formulagammas7.3 Methods and related functions 77a model formula including at least one factor f of length n p , where n p is thenumber of variance parameters among which constraints are to be applied; thelevels of f correspond to the appropriate subset of κ, the n κ vector of varianceparameters. The number of distinct levels in f is less than n p and n p ≤ n κ .a data frame with n p rows in which to resolve the names in formula. That is,gammas must have at least one column, named f.Optional argumentsdrop.unused.levelsif TRUE, unused levels of factors are dropped.interceptif FALSE, the intercept is omitted from the model.na.actionValuehow missing values are handled. Possible options are na.include (thedefault), na.omit or na.fail.a n p ×n c matrix M specifying the variance parameter constraints, where n c is the lengthof the reduced vector of variance components. In the simplest case, for example, wheretwo parameters are constrained to be equal, n c = n p − 1 and the appropriate column ofM will contain ones in the rows corresponding to the parameters in question and zeroselsewhere.Detailsvariance parameter constraints can be specified by a matrix M in κ = Mθ + Es whereκ is the (full) n κ vector of unconstrained components and θ is the n c constrained vector.In asreml, a subset n p of the rows of M, typically those components to be constrained,may be specified. A default data frame (gammas.table) containing one factor, Gammas,whose levels are the n κ names of the variance parameters is returned by asreml whenstart.values=T. The n p row subset of this data frame may provide a convenient objectto hold the factors mentioned in formula. The matrix M is obtained from a call tomodel.frame.default() using formula and the factor(s) corresponding to Gammas.7.3.11 asreml.gammas.edUsageasreml.gammas.ed(param.list, window=T, display=getenv(”DISPLAY”))Required argumentsparam.listOptional argumentswindowa list containing components named G.param and R.param generated froma call to asreml(..., start.values=T). Each of these components is a list objectrepresenting the random and rcov model formulae and contains initialparameter values and constraints.UNIX only. If TRUE, the edit session is opened in a separate window.displayUNIX only. The X display to open the window in if window is TRUE.ValueThe edited version of the list object(s) from calls to asreml.gdflt() and/or asreml.rdflt()internally by asreml().Side effectsA temporary data file beginning with the string gammas is created and removed on exit.DetailsAllows editing of the initial value and constraint components of G and R list structures

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