As men age, their testosterone levels gradually decrease. This may cause a reduction in lean body mass, an increase in fat, and other undesirable changes. Do testosterone supplements reverse some of these effects? A study in the Netherlands assigned 237 men aged 60 to 80 with low or low-normal testosterone levels to either a testosterone supplement or a placebo. The report in the Journal of the American Medical Association described the study as a "double-blind, randomized, placebo-controlled trial." Explain each of these terms to someone who knows no statistics.

1.Explain the meaning of the term "double-blind" study.

• A.Double-blind means that the researchers are not familiar with results concerning the investigated issue.
• B.Double-blind means that the treatment (testosterone or placebo) assigned to a subject was unknown to both the subject and those responsible for assessing C.the effectiveness of that treatment.
• D.Double-blind means that the subjects and those responsible for assessing the effectiveness of the treatment, were not known to each other.
• E.Double-blind means that the treatment (testosterone or placebo) assigned to a subject was unknown to the subject.

2.Explain the meaning of the term "randomized" experiment. True or False: "'Randomized' means that patients were randomly assigned to recieve either the testosterone suppliment or a placebo."

• A.True
• B.False

3.Explain the meaning of the term "placebo-controlled" trial.

• A.Placebo-controlled means that the study is an experiment rather than an observational study.
• B.Placebo-controlled means that the study did not use a placebo group in its design.
• C.Placebo-controlled means that the placebo group showed the same results as the treatment group.
• D.Placebo-controlled means that some of the subjects were given placebo.