Chapter 11

[6 pts]Juvenile free-living ground squirrels utilize responses known as "alarm calls;" that is, vocalizations elicited by a predator. These calls can alert others to danger from a predator. Newly weaned squirrels emerge from the nest at about 25 days of age and enter a noisier world than they are used to. Do the squirrels emerge with automatic responses to alarm signals, or are the responses learned? To answer this question, a biologist played recordings of alarm calls for three distinct samples (by age) of squirrels and observed the squirrels' responses. She reasoned that if the responses were not different for the different age groups, the squirrels must be responding by instinct. On the other hand, if the responses differ with the age of the squirrels the young squirrels must be learning to respond to the alarm calls. Is there convincing evidence that the responses to a chorus of whistles are different for the different age groups? Her data for the responses to a whistle chorus, categorized by age, is presented below: Response to whistle chorus Enter or run to burrow Stand up or freeze | Total 1-5 days old 29 17 46 Age 6-15 days old 38 49 87 16-25 days old |17 21 38 Total 84 87 171 (c) Which chi-square test is appropriate in this setting? Explain your reasoning. (d) State the appropriate hypotheses for performing a chi-square test in this setting. (e) The chi-square test statistic is y? = 4.891. Calculate the P-value. (f) Interpret the P-value. (g) What conclusion would you draw