altered {VGAM}

Altered, Inflated, Truncated and Deflated Values in GAITD Regression

Description

Return the altered, inflated, truncated and deflated values in a GAITD regression object, else test whether the model is altered, inflated, truncated or deflated.

Usage

altered(object, ...)
inflated(object, ...)
truncated(object, ...)
is.altered(object, ...)
is.deflated(object, ...)
is.inflated(object, ...)
is.truncated(object, ...)

Arguments

object

an object of class "vglm". Currently only a GAITD regression object returns valid results of these functions.

...

any additional arguments, to future-proof this function.

Details

Yee and Ma (2023) propose GAITD regression where values from four (or seven since there are parametric and nonparametric forms) disjoint sets are referred to as special. These extractor functions return one set each; they are the alter, inflate, truncate, deflate (and sometimes max.support) arguments from the family function.

Value

Returns one type of ‘special’ sets associated with GAITD regression. This is a vector, else a list for truncation. All three sets are returned by specialsvglm.

Warning

Some of these functions are subject to change. Only family functions beginning with "gaitd" will work with these functions, hence zipoisson fits will return FALSE or empty values.

References

Yee, T. W. and Ma, C. (2024). Generally altered, inflated, truncated and deflated regression. Statistical Science, 39 (in press).

See Also

vglm, vglm-class, specialsvglm, gaitdpoisson, gaitdlog, gaitdzeta, Gaitdpois.

Examples

abdata <- data.frame(y = 0:7, w = c(182, 41, 12, 2, 2, 0, 0, 1))
fit1 <- vglm(y ~ 1, gaitdpoisson(a.mix = 0),
             data = abdata, weight = w, subset = w > 0)
specials(fit1)  # All three sets
altered(fit1)  # Subject to change
inflated(fit1)  # Subject to change
truncated(fit1)  # Subject to change
is.altered(fit1)
is.inflated(fit1)
is.truncated(fit1)