An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory. The appropriate df for doing planned comparisons = _________.
A) 11
B) 6
C) 9
D) 2

Question

An investigator conducts an experiment involving the effects of three levels of a drug on memory. Subjects are randomly assigned to one of three conditions. A different drug level is administered in each condition. Memory is measured 10 minutes after each subject receives the drug. The following scores are recorded. The higher the score, the better the memory.  The appropriate df for doing planned comparisons = _________.
A) 11 
B) 6 
C) 9 
D) 2

Quizplus · Accepted Answer

The appropriate df for doing planned comparisons is calculated as (number of subjects - number of conditions). In this case, there are 12 subjects and 3 conditions, so the df for planned comparisons is (12-3) = 9. Therefore, the correct answer is C.

An Investigator Conducts an Experiment Involving the Effects of Three