The data for this example contains the number of coal miners classified by radiological examination into one of three categories of pneumonoultramicroscopicosilicovolcanoconiosis (known as pneumonoconiosis for short) and by number of years spent working at the coal face divided into eight categories.
data(pneumo)A data frame with 24 observations on the following 3 variables.
Freqnumber of miners
statuspneumoconiosis status - a factor with levels mild normal severe
yearnumber of years service (midpoint of interval)