Relative risk
<p>The ratio of the <a href="/category/glossary/risk">risk</a> (or <a href="/category/glossary/probability">probability</a>) of an <a href="/category/glossary/event">event</a> for one group to the risk of the same event for a second group.</p>
<p><strong>Example</strong></p>
<p>The following <a href="/category/glossary/data">data</a> were collected on a <a href="/category/glossary/random-sample">random sample</a> of students enrolled in a Statistics course at the University of Auckland.<br />
<table border="1">
<tbody>
<tr>
<td align="center"><strong><br />
</strong></td>
<td align="center"><strong>Attendance</strong></td>
</tr>
<tr>
<td align="center"> </td>
<td> </td>
<td align="center">Regular</td>
<td align="center">Not regular</td>
<td align="center"><strong>Total</strong></td>
</tr>
<tr>
<td align="center"><strong>Course<br />
result</strong></td>
<td align="center">Pass<br />
Fail</td>
<td align="center">83<br />
17</td>
<td align="center">19<br />
27</td>
<td align="center">102<br />
44</td>
</tr>
<tr>
<td align="center"> </td>
<td align="center"><strong>Total</strong></td>
<td align="center">100</td>
<td align="center">46</td>
<td align="center">146</td>
</tr>
</tbody>
</table>
<br />
The risk of failing for students with non-regular attendance = 27/46 = 0.5870</p>
<p>The risk of failing for students with regular attendance = 17/100 = 0.17</p>
<p>The relative risk of failing for students with non-regular attendance compared to those with regular attendance = 0.5870/0.17 = 3.5</p>
<p>This can be interpreted as the risk of failing for students with non-regular attendance is about 3.5 times the risk of failing for students with regular attendance.</p>
<p><strong>Curriculum achievement objectives references</strong><br />
Probability: Levels 7, (8)</p>