Blue titmice eat caterpillars. The birds would like lots of caterpillars around when they have young to feed, but they breed earlier than peak caterpillar season. Do the birds learn from one year’s experience when they time breeding the next year? Researchers randomly assigned 7 paris of birds to have a natural supply supplement while feeding their young and another 6 pairs to rely on natural food supply (control). The next year, they measured how many days after the caterpillar peak the birds produced their nestlings.
First, compare the two groups in the first year. The only difference should be the chance effect of the random assignment. The study report says, “In the experimental year, the degree of synchronization did not differ between food-supplemented and control females.” The report gives t = -1.05. What type of t statistic (paired or two-sample) is this? Show that this t leads to the quoted conclusion.
