Sex ratios in South African censuses 1970-1996

The sex ratio of a population or in an age group is the number of males per 100 females in that group. Attention has been drawn to the sex ratios in the 1996 Census of South Africa. A focus has been on the low sex ratios for those age 20-34. Concern has been expressed that these low sex ratios are implausible and differ from what was found in earlier censuses. Some have suspected that these low sex ratios are an indication of poor quality of the 1996 Census overall. The non-African population exhibited low sex ratios in the younger working ages in every census 1970-1996. The dip in sex ratios at the younger working ages for the population of South Africa as a whole was masked by high sex ratios at those ages among Africans in censuses before 1991. The high sex ratios at the younger working ages among Africans were likely due to international inmigrants who were predominantly male and to changes in the geographic regions which were included in the enumeration in the 1980-1991 censuses. These changes in geographic coverage led internal migrants in South Africa, who were mainly male, to have a similar effect on sex ratios by age as international migrants. When sex ratios by age are calculated based on those born in South Africa and for which, as much as possible, similar geographic regions are included, a pattern similar to that seen in 1996 is found in all censuses since 1970.