Winter is the influenza season in North America. Each winter, thousands of elderly and sick people die from the flu and its attendant complications. Consequently, many elderly people receive flu shots in the fall. It has generally been accepted that young healthy North Americans need not receive flu shots because, although many contract the disease, few die from it. However, there are economic consequences. Sick days cost both employees and employers. A study published in the New England Journal of Medicine reported the results of an experiment to determine whether it is useful for young healthy people to take flu shots. A random sample of working adults was selected. Half received a flu shot in November; the other half received a placebo. The numbers of sick days over the next 6-month period were recorded in columns 1 (flu shot) and 2 (placebo). Columns 3 (flu shot) and 4 (placebo) contain the number of visits to the doctor.

a. Can we conclude that those who take flu shots have fewer sick days?

b. Can we conclude that those who take flu shots visit their doctors less frequently?