fitz {hyperdirichlet} | R Documentation

## Fitzmaurice

### Description

Hyperdirichlet distribution corresponding to a dataset of Fitzmaurice et al

### Usage

    fitz(dat , include.missing=TRUE , validated=NULL)

### Arguments

`dat` | A vector corresponding to either male or female data
`include.missing` | Boolean, with default `TRUE` meaning to return the likelihood function for the data including the missing cases, and `FALSE` meaning to include only the data corresponding to complete cases
`validated` | Boolean, with `TRUE` meaning to omit the checks (OK if all elements of `dat` are non-negative) and `FALSE` meaning to check them all (time-consuming)

### Details

Fitzmaurice considered childhood obesity. See the reference for further details.

### Value

Returns a hyperdirichlet distribution (without normalizing factor) corresponding to the observations, either male or female, made by Fitzmaurice et al.

### Note

Pat Altham originally spotted that this dataset could be represented using the hyperdirichlet distribution.

The functional form for replacement “`[<-`()” is used because it is possible to set the `validated` argument to `TRUE`: this suppresses the computationally intensive checking that the distribution is proper.

warning. Setting `validated` to `TRUE` is not recommended in general. It is OK here because the function knows that no elements of `dat` is negative.

### Author(s)

Robin K. S. Hankin

### References

G. M. Fitzmaurice, N. M. Laird, and S. R. Lipsitz 1994. “Analysing incomplete longitudinal binary responses: a likelihood-based approach”. Biometrics, volume 50, pp601-612.

### Examples

      boys  <- c(20,7,9,8, 8, 8,15,150,13,3,2,42,3,1, 6,16,11,1,3,38,14,55,4,33,7,45)
      girls <- c(21,6,6,2,19,13,14,154, 8,1,4,47,4,0,16, 3,11,1,3,25,13,39,5,23,7,47)

      male <- fitz(boys)
      maximum_likelihood(male)

[Package hyperdirichlet version 1.3-8 Index]