HEL A company is testing a new protein shake which they claim works better than their existing brand in improving an athlete's performance.

The company selected 60 athletes from a training camp database, and divided them into three groups. The ages for the groups were

16 to 20 years, 21 to 25 years, and 26 to 30 years. In each group, half of the subjects were asked to use the new protein shake for a month, and

the other half were asked to use the company's existing bradd for a month. The subjects were not informed about which protein shake they

would be using