is.parallel {VGAM} | R Documentation

## Parallelism Constraint Matrices

### Description

Returns a logical vector from a test of whether an object such as a matrix or VGLM object corresponds to a parallelism assumption.

### Usage

    is.parallel.matrix(object, ...)
    is.parallel.vglm(object, type = c("term", "lm"), ...)

### Arguments

`object` | an object such as a constraint matrix or a `vglm` object.
`type` | passed into `constraints`.
`...` | additional optional arguments. Currently unused.

### Details

These functions may be useful for categorical models such as `propodds`, `cumulative`, `acat`, `cratio`, `sratio`, `multinomial`.

### Value

A vector of logicals, testing whether each constraint matrix is a one-column matrix of ones. Note that parallelism can still be thought of as holding if the constraint matrix has a non-zero but constant values, however, this is currently not implemented. No checking is done that the constraint matrices have the same number of rows.

### See Also

`constraints`, `vglm`.

### Examples

    ## Not run:  require("VGAMdata")
    fit <- vglm(educ ~ sm.bs(age) * sex + ethnicity,
                cumulative(parallel = TRUE), head(xs.nz, 200))
    is.parallel(fit)
    is.parallel(fit, type = "lm")  # For each column of the LM matrix

    ## End(Not run)

[Package VGAM version 1.0-3 Index]