: 11 The later definition by Cavalli-Sforza & Bodmer (1971) is currently used: Genetic polymorphism is the occurrence in the same population of two or more alleles at one locus, each with appreciable frequency, where the minimum frequency is typically taken as 1%.
The financial world splits up its calendar into four quarters, each three months long. If January to March is the first quarter, April to June is the second quarter, and so on, though a company's first quarter does not have to begin in January.
Many firms define their fiscal quarters as 13-week periods so that each fiscal year contains 52 weeks, which leaves out one or two day(s) a year. To compensate, one extra week is added every fifth or sixth year and, consequently, one quarter therein comprises 14 weeks.