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?

Check suggested answer 1.

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?

Check suggested answer 2.

3. In what way are the confidence intervals contradictory?

Check suggested answer 3.

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Last updated: 7 November, 2006.

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