touchard (version 2.0.1)

score.delta: Score Test for Poisson vs Touchard

Description

Score test for the extra (with respect to the Poisson) parameter in the Touchard model (Null: \(\delta\) = 0) performed without the need to fit the Touchard model. Analogous likelihood-ratio and Wald tests (which require fitting the full model) are available in the output of toureg.

Usage

score.delta(x, freq = NULL, max = 50, data)

Arguments

x

for univariate data: either an object of class table with the observed counts as classifying factors or the observed counts (raw data) or the unique values of the observed counts in which case the observed frequencies must be given in argument freq; for regression data: an object of class "formula" with the symbolic description of the model to be fitted.

freq

unnecessary (and ignored) if x is a table or the raw data or a formula; must be provided if x is the unique values of the observed counts, in the same order.

max

number of Poisson terms used in calculations of necessary moments

data

data frame containing the variables in the model.

Value

A list with elements

stat

the value the chi-squared test statistic.

pval

the p-value for the test (from chi^2(df=1)).

References

Andrade, BB; Matsushita, RY; Oliveira, SB (submitted) Analyzing Count Data with the Touchard Model. available upon request.

Examples

# NOT RUN {
data(Epilepsy)
score.delta(seizures)

data(Crabs)
score.delta( y ~ weight + color, data = Crabs ) 

# }