R: A small occupational cohort

occup {Epi} | R Documentation

## A small occupational cohort

### Description

This is the data that is behind the illustrative Lexis diagram in Breslow & Day's book on case-control studies.

### Usage

    data(occup)

### Format

A data frame with 13 observations on the following 4 variables.

`AoE`

  a numeric vector, Age at Entry

`DoE`

  a numeric vector, Date of entry

`DoX`

  a numeric vector, Date of eXit

`Xst`

  eXit status `D`-event, `W`-withdrawal, `X`-censoring

### References

Breslow & Day: Statistical Methods in Cancer Research, vol 1: The analysis of case-control studies, figure 2.2, p. 48.

### Examples

    data(occup)
    lx <- Lexis( entry = list( per=DoE, age=AoE ),
                  exit = list( per=DoX ),
          entry.status = "W",
           exit.status = Xst,
                  data = occup )
    plot( lx )
    # Split follow-up in 5-year classes
    sx <- splitLexis( lx, seq(1940,1960,5), "per" )
    sx <- splitLexis( sx, seq(  40,  60,5), "age" )
    plot( sx )

    # Plot with a bit more paraphernalia and a device to get
    # the years on the same physical scale on both axes
    ypi <- 2.5 # Years per inch
    dev.new( height=15/ypi+1, width=20/ypi+1 ) # add an inch in each direction for
    par( mai=c(3,3,1,1)/4, mgp=c(3,1,0)/1.6 )  # the margins set in inches by mai=
    plot(sx,las=1,col="black",lty.grid=1,lwd=2,type="l",
         xlim=c(1940,1960),ylim=c(40,55),xaxs="i",yaxs="i",yaxt="n",
         xlab="Calendar year", ylab="Age (years)")
    axis( side=2, at=seq(40,55,5), las=1 )
    points(sx,pch=c(NA,16)[(sx$lex.Xst=="D")+1] )
    box()
    # Annotation with the person-years
    PY.ann.Lexis( sx, cex=0.8 )

[Package Epi version 2.37 Index]