In a study in the UK, an association was found between the sale of antiarrhythmic drug and an increase in deaths due to asthma. This is an example of
Ans. is 'a' i.e. Ecological study Repeat May 08 www. ucel ac. uk. rlos/specs/rlo_observational_study. doc; http.//cancersupportivecare. com/epidemiology.html] For explanation see May 08
Ecological study
Cohort study
Case reference study
Experimental study