R: Aids Cases in England and Wales

aids {gamlss.data} | R Documentation

## Aids Cases in England and Wales

### Description

The quarterly reported AIDS cases in the U.K. from January 1983 to March 1994 obtained from the Public Health Laboratory Service, Communicable Disease Surveillance Centre, London.

### Usage

    data(aids)

### Format

A data frame with 45 observations on the following 3 variables.

y

  the number of quarterly aids cases in England and Wales: a numeric vector

x

  time in months from January 1983, 1:45 : a numeric vector

qrt

  the quarterly seasonal effect a factor with 4 levels, [1=Q1 (Jan-March), 2=Q2 (Apr-June), 3=Q3 (July-Sept), 4=Q4 (Oct-Dec)]

### Details

The counts y can be modelled using a (smooth) Poisson regression model in time x with the quarterly effects i.e. cs(x,df=7)+qrt. Overdispersion persists, so use a Negative Binomial distribution of type I or II. The data also can be used to find a break point in time, see Rigby and Stasinopoulos (1992).

### Source

Public Health Laboratory Service, Communicable Disease Surveillance Centre, London.

### References

Stasinopoulos, D.M. and Rigby, R. A. (1992). Detecting break points in generalized linear models. Computational Statistics and Data Analysis, 13, 461–471.

### Examples

    data(aids)
    attach(aids)
    plot(x,y,pch=21,bg=c("red","green3","blue","yellow")[unclass(qrt)])
    detach(aids)

[Package gamlss.data version 5.1-0 Index]