Description
lrt.asreml extracts the REML log likelhood and numbers of variance parameters from a sequence of asreml objects, and computes a sequence of pairwise likelihood ratio tests.
Usage
## S3 method for class 'asreml' lrt(..., boundary = TRUE)
Arguments
boundary |
If TRUE (the default) hypothesized parameter values being tested lie on the boundary of the parameter space. |
... |
A sequence of asreml objects assumed nested when arranged in increasing order of number of parameters. |
Details
The models are arranged in increasing order of number of variance parameters and assumed nested in this sequence. If the reduced model is obtained by setting positively-constrained variance parameters in the full model to zero, set boundary to TRUE. In this case the probability is computed using a mixture of chi-square distributions as described in Self and Liang (1987).
Value
A data frame with a row for each successive pairwise test, and columns for the likelihood ratio statistic, degrees of freedom and number of parameters.
References
Self SC and Liang KY (1987). “Asymptotic Properties of Maximum Likelihood Estimators and Likelihood Ratio Tests Under Non-standard Conditions.” Journal of the American Statistical Association, 82, pp. 605-610.