Countries have differed on when they experienced waves and how they responded, and quantifying this temporal relationships between COVID-19 surges or the effects of the emergence of variants is not trivial.
4532
在一些情况下，国家是被动采取应对措施，但在许多其他情况下，则是主动应对。
In some settings the country responses were reactive but in many others they were proactive.
As such, despite the effort to calibrate the model such that it is accurate in different settings, one of the more important limitations to note is that the input data have limited representation and this model generalizes the covariate relationships quantified to settings that may be systematically different from those observed.
4534
最终模型是有意简化的。
The final model is intentionallyparsimonious.
4535
复杂性的降低意味着这样一组缩小的变量集不可能解释在各国观察到的所有变化。
This reduction in complexity means it is not possible for such a reduced set of variables to explain all of the variation that is observed across countries.
While the variables chosen are contextually relevant and are found to explain a significant component of the variation in excess, the underlying population characteristics that drove these differences are too complex to fully capture perfectly in a single global model and, hence, the trade-offs referred to above have had to be made.
4537
因此，就目前而言，这些估计数已是对大流行前24个月可能做出的最佳估计，并存在一定程度的不确定性。
The estimates, therefore, are the best possible at this point in time for the first 24 months of the pandemic and have some degree of uncertainty around them.
4538
世界卫生组织遵循何种程序来计算估计数？
What process did the WHO follow to calculate the estimates?
In February 2021, in collaboration with the United Nations Department of Economic and Social Affairs (UN DESA), WHO convened a Technical Advisory Group (TAG) on COVID-19 Mortality Assessment to advise on the development of analytical methods for estimating excess mortality in all countries.
The COVID TAG is comprised of leading demographers, epidemiologists, data and social scientists and statisticians from a range of backgrounds and geographies.