Answer to Question 1
Content validity relates to the questions that clinicians ask when working with a client. In order to draw good conclusions, the clinician must ask appropriate questions. What will be appropriate in one setting or with one group may not be useful in another context.
People with different lifestyles may not share the same perspective, so a simple question might indicate something quite different across groups. Similarly, a certain behavior will reflect normal functioning in one culture, abnormal functioning in a second, and be completely irrelevant in a third. The potential problems are compounded when a clinician wants to translate a question into a different language; there may not be corresponding ideas in different languages.
In order for test items to be valid for different groups, the concepts have to address the appropriate ideas using appropriate words. Without content validity, answers to individual questions on a test may mislead a clinician entirely.
Answer to Question 2
Experiments involve manipulation of variables and greater control over the research situation than nonexperimental methods do. On the other hand, nonexperiments often have greater complexity to the situation, leading to a more realistic setting. We can draw causal conclusions from experiments, but not from nonexperiments.