Oil spill impact on seabirds. Refer to the Journal of Agricultural, Biological, and Enviro...

Oil spill impact on seabirds. Refer to the Journal of Agricultural, Biological, and Environmental Statistics (Sept. 2000) study of the impact of a tanker oil spill on the seabird population in Alaska, presented in Exercise: Oil spill impact on seabirds. The Journal of Agricultural, Biological, and Environmental Statistics (Sept. 2000) published a study on the impact of the Exxon Valdez tankeroil spill on the seabird population in Prince William Sound, Alaska. A subset of the data analyzed is stored in the EVOS file. Data were collected on 96 shoreline locations (called transects) of constant width, but variable length. For each transect, the number of seabirds found is recorded, as are the length (in kilometers) of the transect and whether or not the transect was in an oiled area. (The first five and last five observations in the EVOS file are listed in the accompanying table.)

Recall that for each of 96 shoreline locations (called transects), the number of seabirds found, the length (in kilometers) of the transect, and whether or not the transect was in an oiled area were recorded. (The data are saved in the EVOS file.) Observed seabird density is defined as the observed count divided by the length of the transect. A comparison of the mean densities of oiled and unoiled transects is displayed in the MINITAB printout on Use this information to make an inference about the difference in the population mean seabird densities of oiled and unoiled transects.