Exercise 3.79 describes a study in which rats showed compassion by freeing a trapped rat. In the study, all six of the six female rats showed compassion by freeing the trapped rat while 17 of the 24 male rats did so. Use the results of this study to give a point estimate for the difference in proportion of rats showing compassion, between female rats and male rats. Then use StatKey or other technology to estimate the standard error and use it to compute an interval estimate for the difference in proportions. Use the interval to determine whether it is plausible that male and female rats are equally compassionate (i.e., that the difference in proportions is zero). The data are available in the dataset Compassionate Rats.

Exercise 3.79

The phrase ‘‘You dirty rat” does rats a disservice. In a recent study, rats showed compassion that surprised scientists. Twenty-three of the 30 rats in the study freed another trapped rat in their cage, even when chocolate served as a distraction and even when the rats would then have to share the chocolate with their freed companion. (Rats, it turns out, love chocolate.) Rats did not open the cage when it was empty or when there was a stuffed animal inside, only when a fellow rat was trapped. We wish to use the sample to estimate the proportion of rats to show empathy in this way. The data are available in the dataset Compassionate Rats.