Incluye bibliografía

Foreword -- Abstract -- Acknowledgements -- 1. Introduction -- 2. Data -- 3. The evidence -- 4. The evidence - another look -- 5. Conclusions -- References -- Appendix table 1: Report number of children ever born

Botswana and Zimbabwe have been acclaimed as being on the vanguard of the demographic transition in sub-Saharan Africa. Key data that are cited to support this claim are the Contraceptive Prevalence Surveys (CPS) and Demographic Health Surveys (DHS) which were conducted in both countries. This paper examines the comparability of these data sources and finds that at least part of the observed decline in aggregate fertility rates in both countries can be attributed to differences in sample composition. In Botswana and Zimbabwe, women of the same cohort are better educated in the second survey relative to the first. Since education and fertility are negatively correlated, this fact explains part - but not all - of the observed fertility decline across the surveys. For example, it accounts for up to half the decline among the cohort of women aged 25 to 34 in Zimbabwe. The DHS included a complete birth history whereas the CPS asked only summary questions about the number of children ever born. There is evidence that differences in the structure of the instruments also raise questions about the comparability of the two data sources.