1. What is the frequency and percentage of COPD patients in the severe airway limitation group recruited for the Eckerblad et al. (2014) study?

2. What proportion of the total sample is retired? What percentage of the total sample is ill?

3. What is the study’s total sample size? What was the frequency and percentage of the total sample that was still in use? Display your calculations and round your answer to the nearest whole percentage point.

4. What is the total percentage of the sample with a smoking history, whether current or former smokers? Is it clinically significant for study participants to have a smoking history? Give a reason for your answer.