At the end of the week their cholesterol is again measured. The best way to determine if there was a significant change in blood cholesterol we should

A study is conducted to examine the impact of a new medicine on the cholesterol level in adult males. A group of 20 subjects have their blood tested to examine their cholesterol level. They are then given the medicine for one week. At the end of the week their cholesterol is again measured. The best way to determine if there was a significant change in blood cholesterol we should