Using a precise numeric scale to define cases is best because it increases the likelihood of identifying "real" cases of pathologic fatigue, which would be of clinical interest.

INCORRECT

The correct answer is (c).

Although it is true that this approach will more precisely define the cases under study, the final result may or may not fulfill the study aims. On the plus side, the distribution of cases available for analysis at the end of the study will probably include mostly clinically relevant cases. This perhaps will allow a more clear description of the type of fatigue associated with this particular therapy. On the minus side however, the approach may exclude patients with milder fatigue, which could lead to a description that misses part of the phenomenon, or yield a skewed distribution for statistical analysis. This could complicate the interpretation of the data or lead to questions about the generalizability of the results.