# Exercise: Diabetes and high blood pressure, part 2

People with diabetes are are increased risk of several health problems, including high blood pressure. In the 2005 M.Sc. questionnaire, respondents were asked

 Have you ever been diagnosed as having: (please tick all that apply) asthma cancer diabetes heart disease high blood pressure other long-term disease (please write in) _________________________

In this exercise, we continue our look at the relationship between reported diabetes and reported high blood pressure.

This is a crosstabulation:

Diabetes High blood pressure Total
No Yes
No 172 20 192
Yes 7 3 10
Total 179 23 202

## Questions

1. The program used for the analysis in Week 7 (Stata 8) gives the following statistics:
Risk difference = 0.196 (95% CI -0.091 to 0.483)
Risk ratio = 2.88 (95% CI 1.02 to 8.10)
Odds ratio = 3.69 (95% CI 0.96 to 14.32)
What do each of these statistics mean?

2. The confidence intervals are all calculated using the Normal distribution and standard error method. Why should these confidence intervals be treated with great caution?

3. In what way are the confidence intervals contradictory?

This page maintained by Martin Bland.
Last updated: 7 November, 2006.