Question 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?
Risk difference = the difference between the proportion of diabetics who report high blood pressure and the proportion of non-diabetics who report high blood pressure, 3/10 - 20/192 = 0.3000 - 0.1042 = 0.196.
Risk ratio = the proportion of diabetics who report high blood pressure divided by the proportion of non-diabetics who report high blood pressure, (3/10) / (20/192) = 0.3000 / 0.1042 = 2.88.
The odds of high blood pressure is the number with high blood pressure divided by the number without high blood pressure.
Odds ratio = the odds of reporting high blood pressure among diabetics divided by the odds of reporting high blood pressure among non-diabetics, (3/7) / (20/172) = 0.4286 / 0.1163 = 3.69.
Back to Exercise: Diabetes and high blood pressure in the 2005 M.Sc. questionnaire, Part 2.
To Applied Biostatistics index.
To Martin Bland's M.Sc. index.
To Martin Bland's home page.
This page maintained by Martin Bland.
Last updated: 20 November, 2006.
Back to top.