Conclusion

This chapter introduced the DHS datasets used to calculate infant mortality rates using the Blacker-Brass and the direct methods. The procedure used to obtain the estimates was also presented and the quality of the DHS data examined. It was acknowledged that effect of HIV/AIDS on infant mortality estimates is significant especially for data pertaining to periods more than two years before the survey. However, correction for this bias was not done as the primary objective of the research is to compare direct method estimates with the ABM and MRBM estimates. Three sources of error that may affect the accuracy of the mortality estimates were identified. These were errors due to missing data, misreported dates of vital events and under reporting of deceased children.

A more detailed summary of the results of the data quality assessment is presented below.

3.4.1 Sampling errors

The sampling errors associated with data in terms of the design effect of using cluster samples instead of simple random sampling were considered to be of limited effect since the main objective of the study was to compare the differences in the estimates between the two methods. Therefore the effect of sampling on the estimates cancels out as the same datasets were used in both methods.

3.4.2 Missing data

Three possible sources of missing data were identified. These were exclusion of eligible women in the initial sampling frame, missing of eligible women who were included in the sampling frame, however not available for interviewing for various reasons and finally omission of questions on vital events by interviewers. There were no further attempts to fill in missing data. As such, data were extracted from the Measure DHS website and analysed in that exact form. Since Measure DHS data are widely used and considered to be reasonably accurate, missing data were considered trivial in this project.

Further, the data were used for comparative purposes; hence missing data did not have an effect.

3.4.3 Number of births in 24 month period

Results shown in Table 3.3 are evidence that using the most recent births only which occurred 24 months before the survey results in severe under estimation of mortality.

Datasets from Bangladesh and Egypt had the highest underestimation of proportion of dead children relative to considering all births reported in the 24-month periods.

Overall most datasets show that using most recent births only underestimates the true proportion of children dead in the 24-month period. Violation of the assumption for converting deaths into mortality measure using the Blacker-Brass method is therefore higher in datasets from Egypt, Cambodia and Indonesia and lowest in Ghana, Ivory Coast and Uganda.

3.4.4 Misreporting of vital events 3.4.4.1 Sex ratios at birth and death

An investigation of the data quality in terms of SRAB and SRAD was executed by country for each survey.

Sex ratios at birth in the range 100 to 106 were considered plausible. Twenty-four DHS datasets had SRAB above 106 and 16 had the sex ratios below 100, an indication of errors in the reporting of deaths and births by sex.

However, the main issue considered on investigation of sex ratios is to check for a particular trend of the ratios moving further back in time from the survey year. Hill (2013) mentions that if the sex ratios increase moving back from survey date this may suggest an under-reporting of female births. If there is under-reporting of females relative to males, this could result in an over estimation of the IMR since there is more male deaths at infancy relative to females. Mortality estimates calculated using the ABM and MRBM are also affected by this misreporting. Out of the 77 datasets used in this study, 13 had increasing SRAB moving back from survey date. Hence, the IMRs in these datasets may have been slightly over –estimated. In other datasets as noted in sub-section 3.3.4 the SRAB decreased with time indicating under-reporting of male births in the recent past. Seven DHS datasets had this pattern. Using the same assumption about more males deaths at infancy the IMRs obtained from these datasets may be slightly over-estimated.

Most of the SRAD were above 100 and this is expected for infant mortality rates.

However, in some datasets the sex ratios were too high indicating a very high mortality level in male babies. There is a notable pattern of very high SRAD in the period 0-24 months before the survey relative to other periods further back in time. Even though the SRAB was above 100, in most datasets, the distribution pattern is not the same as the SRAD. This suggest an over estimation of male deaths for children born within the first 24 months before survey date across all countries. Therefore the IMRs in this period might have been overestimated in these datasets.

The data quality investigations presented may have an effect on the accuracy of the infant mortality measures. It is noted therefore that these estimates may be less accurate compared to a scenario where steps were taken to address the data quality issues such as correction for bias induced by HIV/AIDS and correcting the irregularities of sex ratios. Nonetheless, the primary objective of this research is based on comparing the infant mortality measures of the direct methods with ABM and MRBM estimates hence the inaccuracies may be similar across the different methods.