Question

for 1 and 2, be clear about which groups you are using as your numerator and denominator (baseline/reference group). it may be helpful to arrange the data into a table on a sheet of scratch paper. 1. suppose a study is conducted to assess the association between smoking and cardiovascular disease (cvd). researchers recruited a group of 231 study participants then categorized them according to smoking and disease status: 111 are smokers, while 40 smokers and 32 non-smokers have cvd. use r to calculate the relative risk of cvd and interpret the result. 2. suppose another study is conducted to assess the association between smoking and cvd, but researchers use a different design: 90 individuals with cvd and 110 individuals without cvd are recruited. 40 of the individuals with cvd are smokers, and 80 of the individuals without cvd are non-smokers. a. is relative risk an appropriate measure of association for these data? explain your answer. b. calculate the odds of cvd among smokers and the odds of cvd among non- smokers. c. calculate and interpret the odds ratio of cvd, comparing smokers to non- smokers. d. what would an odds ratio of cvd (comparing smokers to non-smokers) equal to 1 represent, in terms of the association between smoking and cvd? what would an odds ratio of cvd less than 1 represent?

Answer 1

a. Relative risk is not appropriate for the second study. b. Calculate the odds of cvd for smokers and non-smokers. c. Calculate and interpret the odds ratio of cvd for smokers vs non-smokers. d. Interpret odds ratio of cvd equal to 1 and less than 1.

Step-by-step explanation:

a. Relative risk is not an appropriate measure of association for the second study design. The relative risk requires the data to be organized into a 2 x 2 table, where the numerator represents the exposed group and the denominator represents the unexposed group. In the second study design, both smokers and non-smokers have cardiovascular disease, which does not fit this structure.

b. To calculate the odds of cvd among smokers, divide the number of smokers with cvd by the number of smokers without cvd. To calculate the odds of cvd among non-smokers, divide the number of non-smokers with cvd by the number of non-smokers without cvd.

c. To calculate the odds ratio of cvd comparing smokers to non-smokers, divide the odds of cvd among smokers by the odds of cvd among non-smokers. The interpretation of the odds ratio is that smokers are x times as likely to have cvd compared to non-smokers.

d. An odds ratio of cvd equal to 1 represents no association between smoking and cvd. An odds ratio of cvd less than 1 represents a decreased likelihood of cvd among smokers compared to non-smokers.