ize="2"><sup>r
</sup></font><font face="Arial" color="#000100" size="3">)<br>&nbsp;&nbsp;&nbsp;<br>where t
</font><font face="Arial" color="#000100" size="3"><sub>i
</sub></font><font face="Arial" color="#000100" size="3"> is the failure time of an individual with covariate vector 
</font><font face="Arial" color="#000100" size="3"><strong>z
</strong></font><font face="Arial" color="#000100" size="2"><sub>i
</sub></font><font face="Arial" color="#000100" size="3"><sub> 
</sub></font><font face="Arial" color