title: A new index for the intensity of natural selection.
abstract: A new index for the intensity of natural selection is proposed, based upon the double exponential model for fitness functions. This index is defined as a variance and is such that a value of zero indicates no selection while a value of one indicates quite strong selection. The use of the index is demonstrated using published data on the survival of human infants with different birth weights and gestation times.
mesh_terms: D005075:Biological Evolution; D008954:Models, Biological; D011336:Probability; D012641:Selection, Genetic