poisson.anova: Analysis of variance with a count variable

In Rfast: A Collection of Efficient and Extremely Fast R Functions

Analysis of variance with a count variable

Description

Analysis of variance with a count variable.

Usage

poisson.anova(y, ina, logged = FALSE)
geom.anova(y, ina, type = 1, logged = FALSE)
quasipoisson.anova(y, ina, logged = FALSE)

Arguments

y	A numerical vector with discrete valued data, i.e. counts.
ina	A numerical vector with discrete numbers starting from 1, i.e. 1, 2, 3, 4,... or a factor variable. This is suppose to be a categorical predictor. If you supply a continuous valued vector the function will obviously provide wrong results.
type	This argument is for the geometric distribution. Type 1 refers to the case where the minimum is zero and type 2 for the case of the minimum being 1.
logged	Should the p-values be returned (FALSE) or their logarithm (TRUE)?

Details

This is the analysis of variance with Poisson or geometric distributed data. What we do is a log-likelihood ratio test. However, this is exactly the same as Poisson regression with a single predictor variable who happens to be categorical. Needless to say that this is faster function than the glm command in R. For the same purpose with a Bernoulli variable use g2Test. The quasinpoisson.anova is when in the glm function you specify family = quasipoisson. This is suitable for the case of over or under-dispersed data.

Value

A vector with two values, the difference in the deviances (or the scale difference in the case of quasi poisson) and the relevant p-value. The quasipoisson.anova also returns the estimate of the \phi parameter.

Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <[e-mail]> and Manos Papadakis <[e-mail]>.

See Also

logistic.cat1, g2Test, poisson.anovas, anova, poisson_only, poisson.mle

Examples

y <- rpois(300, 10)
ina <- rbinom(300, 3, 0.5) + 1 
a1 <- poisson.anova(y, ina) 
a2 <- glm(y ~ ina, poisson) 


res<-anova(a2, test = "Chisq")

y <- rgeom(300, 0.7)
res<-geom.anova(y, ina) 

Rfast documentation built on Nov. 9, 2023, 5:06 p.m.