Fafo Institute of Applied International Studies, Oslo, Norway.
PLoS Med. 2012;9(8):e1001289. doi: 10.1371/journal.pmed.1001289. Epub 2012 Aug 28.
Child mortality estimates from complete birth histories from Demographic and Health Surveys (DHS) surveys and similar surveys are a chief source of data used to track Millennium Development Goal 4, which aims for a reduction of under-five mortality by two-thirds between 1990 and 2015. Based on the expected sample sizes when the DHS program commenced, the estimates are usually based on 5-y time periods. Recent surveys have had larger sample sizes than early surveys, and here we aimed to explore the benefits of using shorter time periods than 5 y for estimation. We also explore the benefit of changing the estimation procedure from being based on years before the survey, i.e., measured with reference to the date of the interview for each woman, to being based on calendar years.
Jackknife variance estimation was used to calculate standard errors for 207 DHS surveys in order to explore to what extent the large samples in recent surveys can be used to produce estimates based on 1-, 2-, 3-, 4-, and 5-y periods. We also recalculated the estimates for the surveys into calendar-year-based estimates. We demonstrate that estimation for 1-y periods is indeed possible for many recent surveys.
The reduction in bias achieved using 1-y periods and calendar-year-based estimation is worthwhile in some cases. In particular, it allows tracking of the effects of particular events such as droughts, epidemics, or conflict on child mortality in a way not possible with previous estimation procedures. Recommendations to use estimation for short time periods when possible and to use calendar-year-based estimation were adopted in the United Nations 2011 estimates of child mortality.
来自人口与健康调查（DHS）调查和类似调查的完整生育史的儿童死亡率估计是用于跟踪千年发展目标 4 的主要数据来源之一，该目标旨在将 1990 年至 2015 年期间五岁以下儿童死亡率减少三分之二。根据 DHS 计划开始时的预期样本量，这些估计通常基于 5 年的时间段。最近的调查样本量比早期调查大，在这里，我们旨在探索使用比 5 年更短的时间段进行估计的好处。我们还探讨了改变估计程序的好处，从基于调查前几年的方法（即根据每位妇女接受访谈的日期进行衡量）改为基于日历年的方法。
使用刀切方差估计法计算了 207 项 DHS 调查的标准误差，以探讨近期调查中的大样本在多大程度上可以用于基于 1、2、3、4 和 5 年时间段进行估计。我们还重新计算了基于日历年的估计值。我们证明，对于许多最近的调查，确实可以进行 1 年周期的估计。
在某些情况下，使用 1 年周期和基于日历年的估计可以减少偏差，这是值得的。特别是，它可以以以前的估计程序不可能的方式跟踪特定事件（如干旱、流行病或冲突）对儿童死亡率的影响。联合国在 2011 年儿童死亡率估计中建议在可能的情况下使用短期估计，并使用基于日历年的估计。
