R: Many tests for the dispersion parameter in Poisson...

Many tests for the dispersion parameter in Poisson distribution {Rfast} | R Documentation

## Many tests for the dispersion parameter in Poisson distribution

### Description

Many tests for the dispersion parameter in Poisson distribution.

### Usage

    colpoisdisp.tests(y, alternative = "either", logged = FALSE)
    colpois.tests(y, logged = FALSE)

### Arguments

`y` | A numerical matrix with count data, 0, 1,...
`alternative` | Do you want to test specifically for either over or underspirsion ("either"), overdispersion ("over") or undersispersion ("under")?
`logged` | Set to TRUE if you want the logarithm of the p-value.

### Value

A matrix with two columns, the test statistic and the (logged) p-value.

### Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <mtsagris@uoc.gr> and Manos Papadakis <papadakm95@gmail.com>.

### References

Yang Zhao, James W. Hardin, and Cheryl L. Addy. (2009). A score test for overdispersion in Poisson regression based on the generalized Poisson-2 model. Journal of statistical planning and inference 139(4):1514-1521.

Dimitris Karlis and Evdokia Xekalaki (2000). A Simulation Comparison of Several Procedures for Testing the Poisson Assumption. Journal of the Royal Statistical Society. Series D (The Statistician), 49(3): 355-382.

Bohning, D., Dietz, E., Schaub, R., Schlattmann, P. and Lindsay, B. (1994) The distribution of the likelihood ratio for mixtures of densities from the one-parameter exponential family. Annals of the Institute of Statistical Mathematics, 46(): 373-388.

### See Also

`poisson.mle, negbin.mle, poisson.anova, poisson.anovas, poisson_only`

### Examples

    y <- matrix(rnbinom(100* 50, 10, 0.6), ncol = 50)
    a1 <- colpoisdisp.tests(y, "over")
    b1 <- colpois.tests(y)

    y <- matrix(rpois(100* 50, 10), ncol = 50)
    a2 <- colpoisdisp.tests(y, "either")
    b2 <- colpois.tests(y)
    y <- NULL

[Package Rfast version 2.0.4 Index]