Worldwide, different societies variously encourage, accept or outlaw polygamy. In societies which allow or tolerate polygamy, in the vast majority of cases the form accepted is polygyny. According to the "Ethnographic Atlas Codebook" (1998), of 1,231 societies noted, 588 had frequent polygyny, 453 had occasional polygyny, 186 were monogamous and 4 had polyandry - although more recent research suggests that polyandry may occur more commonly than previously thought. In cultures which practice polygamy, its prevalence among that population often correlates with class and socioeconomic status.