alteredvglm: Altered, Inflated, Truncated and Deflated Values in GAITD...

alteredR Documentation

Altered, Inflated, Truncated and Deflated Values in GAITD Regression


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


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


Yee and Ma (2021) 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 arguments from the family function.


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.


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.


Yee, T. W. and Ma, C. (2022). Generally–altered, –inflated, –truncated and –deflated regression, with application to heaped and seeped data. In preparation.

See Also

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


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

VGAM documentation built on July 6, 2022, 5:05 p.m.