Age Heaping and Cancer Rate Estimation in Nigeria

Age heaping is an important source of demographic bias in many countries. There is little scholarship on the effect of age heaping on cancer rate estimation. We use Nigerian demographic and cancer registry data to (1) quantify age heaping in states and within cancer registries using the Myers Blended Index and (2) examine the effect of residual age heaping bias on age standardized cancer rates (ASRs). We find severe age heaping at the level of the state and within cancer registries which is more pronounced in the north than the south. Further, we find less age heaping among women in registries compared to both men in registries and to women in the general population. Lastly, we find little evidence of residual age heaping bias comparing ASRs estimated using the population data as given (Base) to Arriaga and Strong smoothed imputed populations. The geographic results likely reflect economic and educational disparities between the north and south. The gender difference may signify that higher educated women do more screening and seek care more often. Lastly, the absence of ASR differences between the Base and smoothed populations provides evidence that age heaping may not seriously bias ASRs in countries with severe age heaping. Minnesota Population Center Working Paper Series