Question: Alcohol and Heart Attacks. Many studies have found that people who drink alcohol in moderation have lower risk of heart attack than other non-drinkers or heavy drinkers. Does alcohol consumption also improve survival after a heart attack? One study followed 1913 people who were hospitalized after severe heart attacks. In the year before their heart attacks, 47% of these people didn’t drink, 36 % drank moderately and 17% drank heavily. After 4 years, fewer of the moderate drinkers had died. Is this an observational study or an experiment? Why? What are the explanatory and response variables?