The diameters (Y) of three species of pine trees were compared at each of four locations, using samples of five trees per species at each location. The resulting data are given in the following table.

a. Comment on whether each of the two factors should be considered fixed or random.
b. Use the following partially completed ANOVA table to carry out your analysis, first considering both factors as fixed and then considering a mixed model with "locations" treated as random. Compare your conclusions.