#000100" size="3"><br>Dellaportas and Smith (1993) analyse data from Grieve (1987) on photocarcinogenicity in four groups, each containing 20 mice, who have recorded a survival time and whether they died or were censored at that time. A portion of the data, giving survival times in weeks, are shown below. A 
</font><font face="Arial" color="#000100" size="3"><em>* 
</em></font><font face="Arial" color="#000100" size="3">indicates censoring.<br><center><br>
</font><font face="Arial" color="#000100" size="2">