Statistics Exercise sheet 10 1. In a survey on consumption and dietary habits, 317 people were asked about their use of nicotine and caffeine. The respondents were divided into smokers and non-smokers (less than 5 cigarettes per week) as well as into coffee drinkers (more than one cup per day) and non-coffee drinkers: Nicotine Coffee smokers Coffe drinkers 100 39 non-smokers 103 75 Non-Coffe drinkers a) Calculate row and column percentages and interpret the results. b) Using a x² test at the 5% level of significance, test the null hypothesis that nicotine consump- tion is independent of caffeine consumption. (i) To do this, state the null and alternative hypotheses, (ii) calculate the frequencies expected under the null hypothesis, (iii) calculate the test statistic relevant to the test, (iv) compare the test statistic to the critical value, (v) interpret the test result. c) Unify your findings from the above points into a final interpretation.
