Question

Shoe size > 9

Pair Case Control
1      Yes     No
2       No    No
3       No       Yes
4      Yes      Yes
5       No       Yes

1. Compute the proper measure of association.
2. Interpret your results.
3. If you were to investigate a rare cancer in Lynchburg, where might you look for data?
4. What would be necessary legally and ethically to be able to utilize this data set(s)?

Answer 1

Answer :)

First, make a table like the below:

Status	Shoe size >9 (Yes) or Diseased	Shoe size >9 (No) or Non-diseased	Population	Cumulative incidence (CI)
Exposed (Case)	2	3	5	0.4
Non-exposed (control)	3	2	5	0.6

In the table, the data can divide into two categories- exposed that are cases and non-exposed that are controls. There are 2 cases where shoe size is greater than 9 while the other 3 have not. In controls, 3 have shoe size greater than 9 while the other 2 have not. Calculate cumulative incidence of each category of status by the following formula:

Cumulative incidence = Total Diseased/Total Population

To find out the measure of association, calculate risk ratio by using the following formula:

Risk ratio = CI of Exposed/ CI of control

Risk ratio = 0.4/ 0.6

Risk ratio = 0.67

The risk ratio is less than 1, which suggests the reduced risk in the exposed (Case) group. Their risks are reduced. Therefore, shoe size >9 is associated with the disease by a risk factor of 0.67 in comparison to those who are controlled.

To find out data for cancer cases in Lynchburg, contact the Virginia Department of Health where the Virginia Cancer Registry contains all data for Lynchburg.

Researchers using these data must not expose the personal information of people and not be indulging in illegal activities other than the research hypothesis.