, where Ej is the average emergence on host genotype j, Emax is the maximum emergence of the parasite population observed on any host genotype of any host species tested at the same location, and is the number of genotypes tested of host species k.  Mean relative emergence ranges from 0 to 1 where, for example, a mean relative emergence of 0.5 on maize would indicate that for a given parasite population, on average half of the individuals emerge on genotypes of maize compared to the maximum emergence in an experiment.  Similarly, a mean relative emergence close to 1 on sorghum would indicate that a parasite population specializes on sorghum.