solution

In the Kemp’s ridley turtle example, we tested whether the sex ratio has shifted. The data were observational, that is, turtles used in the data set were not randomly selected from the population, rather, these were turtles stranded on the beach. One particular feature of the data is the large difference in the number of turtles observed during the two time periods. Suppose that the data from the first time period (1983– 1989) were collected by regularly scheduled beach patrols throughout the year, while the data in the second time period (1990–2001) also include observations reported by tourists. Discuss the possible causes of the observed sex ratio differences.