A psychologist wishes to determine whether short-term memory scores are affected by the type of medication in hyperactive children. Sixty hyperactive children (30 boys and 30 girls) were randomly assigned to receive either Cylert or Ritalin (two kinds of amphetamines that are central nervous system stimulants). Their short-term memory was tested on a 20-point scale (where 0 = no memory and 20 = perfect memory).$\begin{array} { c c c c c c }
\hline & \text { Boys } & && { \text { Girls } } \
\hline \text { Cylert } & \text { Placebo } & \text { Ritalin } & \text { Cylert } & \text { Placebo } & \text { Ritalin } \
\hline 12 & 5 & 3 & 5 & 4 & 12 \
10 & 6 & 2 & 6 & 6 & 9 \
13 & 7 & 5 & 2 & 7 & 14 \
10 & 6 & 6 & 4 & 6 & 13 \
9 & 4 & 1 & 3 & 5 & 9 \
12 & 5 & 4 & 2 & 4 & 12 \
13 & 6 & 2 & 4 & 5 & 8 \
10 & 7 & 6 & 6 & 6 & 15 \
11 & 5 & 1 & 2 & 7 & 12 \
12 & 7 & 5 & 4 & 7 & 11 \
\hline
\end{array}$
-The degrees of freedom for the interaction are
A)1
B)2
C)54
D)59

Question

A psychologist wishes to determine whether short-term memory scores are affected by the type of medication in hyperactive children. Sixty hyperactive children (30 boys and 30 girls) were randomly assigned to receive either Cylert or Ritalin (two kinds of amphetamines that are central nervous system stimulants). Their short-term memory was tested on a 20-point scale (where 0 = no memory and 20 = perfect memory).$\begin{array} { c c c c c c } 
\hline & \text { Boys } & && { \text { Girls } } \
\hline \text { Cylert } & \text { Placebo } & \text { Ritalin } & \text { Cylert } & \text { Placebo } & \text { Ritalin } \
\hline 12 & 5 & 3 & 5 & 4 & 12 \
10 & 6 & 2 & 6 & 6 & 9 \
13 & 7 & 5 & 2 & 7 & 14 \
10 & 6 & 6 & 4 & 6 & 13 \
9 & 4 & 1 & 3 & 5 & 9 \
12 & 5 & 4 & 2 & 4 & 12 \
13 & 6 & 2 & 4 & 5 & 8 \
10 & 7 & 6 & 6 & 6 & 15 \
11 & 5 & 1 & 2 & 7 & 12 \
12 & 7 & 5 & 4 & 7 & 11 \
\hline
\end{array}$
-The degrees of freedom for the interaction are
A)1
B)2
C)54
D)59

Quizplus · Accepted Answer

The degrees of freedom for the interaction in a two-way ANOVA are calculated by multiplying the degrees of freedom for each factor. Here, we have two factors: type of medication (Cylert, Placebo, Ritalin) and gender (Boys, Girls). The degrees of freedom for medication are 2 (3 levels - 1) and for gender are 1 (2 levels - 1). Therefore, the degrees of freedom for the interaction are 2 * 1 = 2.

A Psychologist Wishes to Determine Whether Short-Term Memory Scores Are