# Exercise: Alcohol consumption and sex

In the 2005 M.Sc. questionnaire, adult respondents were asked whether they were female or male and how much alcohol they usually consumed in a week.

The distribution of reported alcohol consumption by sex is shown in the following graph:

The data may be summarised as follows:

Number Mean   SD
Female 101 6.6 6.4
Male 76 9.8 11.0

The difference in mean alcohol consumption, male minus female, is 3.2 units/week. The 95% confidence interval for the difference is 0.4 to 6.0 units/week, P = 0.02.

Question 2. What methods could be used to calculate the confidence interval for the difference in mean alcohol consumption? Which should we use here and why?

Question 3. What does ‘The 95% confidence interval is 0.4 to 6.0 units/week’ mean and what conclusion could we draw from it?

Respondents were asked whether they ever been diagnosed as having high blood pressure. The distribution of reported alcohol consumption by reported hypertension is shown in the following graph:

The data may be summarised as follows:

Number Mean   SD
Hypertensive 21 8.6 7.8
Normotensive 157 7.8 8.9

The difference in mean alcohol consumption, hypertensive minus normotensive, is 1.0 units/week. The 95% confidence interval for the difference in mean is –2.7 to +4.9 units/week, P = 0.6.

6. If we accept the confidence interval and P value, what can we conclude about hypertension and alcohol consumption? What should we NOT conclude?