Regarding the practice of manipulating two variables simultaneously in a single-subject study, one should conclude:
A) This practice is acceptable as researchers now believe that we can tease out interactive effects.
B) This practice is acceptable because we can statistically manipulate individual variables.
C) This practice is unsound because in so doing we are unable to assess effects of either variable.
D) This practice is unsound because in so doing we confuse the participant as a threat to validity.

Question

Quizplus · Accepted Answer

Manipulating two variables simultaneously in a single-subject study is unsound because it makes it difficult to assess the effects of either variable. This is because we cannot isolate the influence of each variable, and therefore cannot draw definitive conclusions about the effect of either variable. This can compromise the validity of the study and lead to questionable or unreliable results.

Regarding the Practice of Manipulating Two Variables Simultaneously in a Single-Subject