Species diversity is often used as a simple way to compare the biodiversity of different regions of the world. A student read that species diversity decreases with increasing distance from the equator. The latitude at the equator is 0°. Latitudes increase north and south of the equator. The student selected data from a database which holds records of the annual bird count in North America. This annual count is carried out each year during one day in the winter. Volunteers count all the species of birds that they observe in each location. The area of each location is the same size. The student found data from 17 sample locations within the Delmarva Peninsula on the east coast of the USA for 2005. Fig. 2.1 shows the 17 locations within the Delmarva Peninsula. [Figure 2.1] The student used the data to see if there was any relationship between the latitudes of the sample locations and the number of species recorded at each location. The data are shown in Fig. 2.2.