The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below. A 50-yard freestyle time is recorded for each swimmer. The resulting times (seconds) are shown below. Which statistical test would you choose to compare the two groups? $$\begin{array} { c c c }
& { \text { Age Group } } \
\text { Obs } & 25 - 34 \text { Yrs } & 35 - 44 \text { Yrs } \
1 & 26.26 & 31.08 \
2 & 28.44 & 28.63 \
3 & 26.61 & 25.65 \
4 & 29.74 & 31.81 \
5 & 26.94 & 27.22 \
6 & 26.31 & 30.56 \
7 & 34.68 & 33.38 \
8 & 22.55 & 30.82 \
& & \
\text { Mean } & 27.69 & 29.89 \
\text { St Dev } & 3.50 & 2.54
\end{array}$$

Question

The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below. A 50-yard freestyle time is recorded for each swimmer. The resulting times (seconds) are shown below. Which statistical test would you choose to compare the two groups? $$\begin{array} { c c c } 
&  { \text { Age Group } } \
\text { Obs } & 25 - 34 \text { Yrs } & 35 - 44 \text { Yrs } \
1 & 26.26 & 31.08 \
2 & 28.44 & 28.63 \
3 & 26.61 & 25.65 \
4 & 29.74 & 31.81 \
5 & 26.94 & 27.22 \
6 & 26.31 & 30.56 \
7 & 34.68 & 33.38 \
8 & 22.55 & 30.82 \
& & \
\text { Mean } & 27.69 & 29.89 \
\text { St Dev } & 3.50 & 2.54
\end{array}$$

Quizplus · Accepted Answer

Since the variances of the two groups are not known and they are independent, we should use the t-test for independent samples with unknown variances.

The Coach of an Adult Master's Swim Class Selected Eight