In a Study of Captive Nectar-Feeding Bats (Leptonycteris Sanborni), Data $R W G=\frac{\text { PostFeeding - Original }}{\text { Original }}$

Essay

In a study of captive nectar-feeding bats (Leptonycteris sanborni), data were gathered on nectar intake over a five-minute flight period. The bats were randomly selected for the study. Investigators are interested in the differences in weight gain for males and females. The bats were weighed before and after feeding, and the relative weight gain was calculated for each animal using the formula:

$R W G=\frac{\text { PostFeeding - Original }}{\text { Original }}$

$\begin{array}{|c|c|c|c|c|}\hline \text { Bat \# } & \text { Sex } & \begin{array}{c}\text { Original } \\\text { Weight }\end{array} & \begin{array}{c}\text { Post-feeding } \\\text { Weight }\end{array} & \begin{array}{c}\text { Relative } \\\text { Weight gain }\end{array} \\\hline\mathbf{1} & \mathrm{F} & 18.6 & 19.8 & 0.065 \\\mathbf{2} & \mathrm{F} & 18.5 & 20.8 & 0.124 \\\mathbf{3} & \mathrm{F} & 18.6 & 20.0 & 0.075 \\\mathbf{4} & \mathrm{F} & 20.4 & 21.9 & 0.074 \\\mathbf{5} & \mathrm{F} & 21.5 & 23.0 & 0.070 \\\mathbf{6} & \mathrm{F} & 20.3 & 22.0 & 0.084\\\mathbf{7} & \text { F } & 17.0 & 18.5 & 0.088 \\\mathbf{8} & \mathrm{F} & 17.0 & 19.0 & 0.118 \\\mathbf{9} & \mathrm{F} & 17.5 & 19.2 & 0.097 \\\mathbf{1 0} & \mathrm{F} & 19.7 & 21.0 & 0.066 \\\mathbf{1 1} & \mathrm{M} & 18.2 & 20.2 & 0.110 \\\mathbf{1 2} & \mathrm{M} & 20.2 & 22.3 & 0.104 \\\mathbf{1 3} & \mathrm{M} & 19.0 & 20.5 & 0.079\\\mathbf{1 4} & \mathrm{M} & 17.3 & 18.5 & 0.069 \\\mathbf{1 5} & \mathrm{M} & 17.8 & 19.0 & 0.067 \\\mathbf{1 6} & \mathrm{M} & 19.5 & 21.6 & 0.108 \\\mathbf{1 7} & \mathrm{M} & 21.0 & 22.8 & 0.086 \\\mathbf{1 8} & \mathrm{M} & 17.0 & 18.4 & 0.082 \\\mathbf{1 9} & \mathrm{M} & 18.3 & 19.3 & 0.055\\\hline\end{array}$



Consider constructing a $95 \%$ confidence interval for the population difference in mean weight gains for male and female bats.
a) Using a graphic display of your choice, show that it is appropriate to use the $t$ procedure to construct a confidence interval.




b) Calculate and interpret the $95 \%$ confidence interval in the context of the problem.





c) Do you feel these results can be generalized to non-captive bats? Why or why not?