A psychologist wishes to determine whether drinking coffee improves one's mood. The psychologist hangs out at the Café Coffay and asks customers to fill out a 10-point good-mood, bad-mood questionnaire (where 10 = great mood and 1 = bad mood) before and after their first cup of coffee that day. The research question is whether there is any evidence that drinking coffee improves mood.$\begin{array}{lll}&\text { Before Mood Rating }&\text { After Mood Rating }\
\hline \text { Participant 1 } & 5 & 9 \
\text { Participant 2 } & 3 & 8 \
\text { Participant 3 } & 9 & 9 \
\text { Participant 4 } & 3 & 8 \
\text { Participant 5 } & 2 & 7 \
\text { Participant 6 } & 4 & 9 \
\text { Participant 7 } & 1 & 10\
\text { Participant 8 } & 8 & 8 \
\text { Participant 9 } & 6 & 5 \
\text { Participant 10 } & 7 & 7 \
\text { Participant 11 } & 4 & 3 \
\text { Participant 12 } & 3 & 10 \
\text { Participant 13 } & 8 & 7 \
\text { Participant 14 } & 7 & 9 \
\text { Participant 15 } & 5 & 9\\hline
\end{array}$
-The value of the numerator in the dependent t test formula for this problem is approximately
A)0.08
B)2.87
C)5.00
D)7.87

Question

Quizplus · Accepted Answer

The numerator in the dependent t test formula is the difference between the means of the two groups. In this case, the mean of the before mood ratings is 4.73 and the mean of the after mood ratings is 7.60. Therefore, the numerator is 7.60 - 4.73 = 2.87.

A Psychologist Wishes to Determine Whether Drinking Coffee Improves One's