Ibadan Journal of the Social Sciences
Volume 4, No. 2, 2006
Pages 89-102

DOI: 10.36108/ijss/6002.40.0220

Reliability of Age-Sex Data in Demographic Analysis: An assessment of Nigeria’s empirical evidence, 1990-2003

Chuks J. Mba

Regional lastitute for Population Studies
University of Ghana, Legon, Ghana


This study investigates the accuracy of age-sex data in Nigeria for the period 1990-2003. The data used were taken from the household schedules of Nigeria’s demographic and health surveys. Yearly data suggest that Nigerian females are more likely to correctly report their ages than their male counterparts as the Whipple’s Index results showed 267 in 1990, 233 in 1999, and 209 in 2003 among females, while the corresponding values among males were 302 in 1990, 253 in 1999, and 226 in 2003. Digits 0 and 5 are preferred (with digit 0 preferred more), while the other digits are avoided. During the period under review, digits most avoided by both sexes were 1 and 9. On the whole, the patterns of digit preference by sex have remained largely the same. More importantly, digit preference and avoidance in Nigeria is high. Myers’ Index values, which parallel those of the digit preference index (DPI) declined from 79 in 1990 to 42 in 2003 for males, and from 56 in 1990 to 40 in 2003 for females. Bachi’s index values similarly fell from 40 in 1990 to 21 in 2003 among males, and from 28 in 1990 to 20 in 2003 among females. These findings reveal substantial inaccuracies in the Nigerian data files. The sex ratio at birth varied from 98 in 1990 to 107 in 1999, and then to 104 in 2003. Overall sex ratio was 98 in 1990 and 99 in 2003, lower than the model sex ratio range of 100-107 for Africa. The UN joint score increased from 111 in [990 to 152 in 1999 and then declined to 116 in 2003. The joint score values from data quality assessment also indicate inaccuracies. Nigeria needs accurate statistics for development planning.
Keywords: Digit preference, Myer’s Index, sex ratio, Whipple’s Index, age ratio

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