Family Support Objects

USAGE:

glm.links[function/expression name , link name] 
glm.variances[function/expression name , variance name] 
glm.weights[[link name, variance name]] 

These are all matrix objects used in the construction of family objects.
The object glm.links is a matrix of mode "list", and has dimension c(5,8). The 8 columns represent each of the link functions logit, probit, cloglog, identity, inverse, log, "1/mu^2", and sqrt. The first row name is simply a character name for the link function. The rows link, inverse and deriv contain functions that define the link function and its derivative. Both link and deriv take a single argument mu, while inverse takes the argument eta. For example, > glm.links[["link","logit]] function(mu) log(mu/(1 - mu)) > The final row initialize is an expression that gets evaluated before the Fisher-scoring iterations in glm or local-scoring iterations in gam commence. This is used to initialize the linear- or additive predictor, as well as to set particular constants, transform the response, and so on.
The object glm.variances is a matrix of dimension c(3,5), with columns representing the 5 variance functions "constant", "mu(1-mu)", "mu", "mu^2" and "mu^3". The first row is once again a name, while the other two represent the variance and deviance functions.
These objects are used by the function make.family, and indirectly by glm, quasi, etc., when constructing family objects. See the documentation of family and make.family for additional details.
The object glm.weights is used by the function glm.weight, in turn by make.family; while glm.weight will construct a default weight expression from the variance and deriv functions, the non-NULL entries in glm.weights give simplified expressions for particular link-variance pairings.

SEE ALSO:

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