Unravelling sex ratios, what can they tell us about census, population estimates and recent trends in migration?
This paper aims to understand the sex ratio observed in England and Wales (EW) population estimates and the extent to which its pattern could reflect recent trends in migration. In particular it looks at the changes in sex ratio patterns resulting from the population estimates derived from the 2001 Census and aims to identify plausible explanations for its subsequent trend. In most countries, low sex ratios at younger working ages are observed in census data, which leads to questions about their plausibility. One possibility may be that geographically mobile young males are more likely to get undercounted relative to their female counterparts. Even after using statistical techniques to adjust for under enumeration a sharp drop in the sex ratio was observed in the EW Census of 2001 around age 18 and similarly appears in the mid-2001 population estimates based on the Census. A noticeable feature of population estimates for subsequent years is that the drop observed around 2001 is ageing
