Question

by A researcher investigates whether calorie intake has an effect on the incidence df chronic disease. A sample of 120 rhesus monkeys were divided into two equal groups. Over the span of 10 years, one group ate without limit (well-fed) and the other group consumed only 70% as many calories as the first group (low-cal). In the well-fed group. 25 animals experienced some form of chronic disease compared to 13 in the low-calorie group. Disease No disease Total 47 60 Low-cal 13 Well-fed Total 25 82 60 120 3835 1) Wirite the null and alternate hypothesis for a test of independence for the table. (2 marks) i) Calculate the expected frequencies for all cells assuming that the null hypothesis is (4 marks) true. iii) At a-0.05, determine whether calorie intake has an effect on the incidence of chronic (9 marks) disease.

Answer 1

Here we use the Chi-square test of independence between two categorical variables as follows--