This is because in fat-tailed distributions, the mean is affected by outliers and therefore one needs many years of data to arrive at a stable estimate.

在厚尾分布中，平均值会受到异常值的影响，因而需要好多年的数据才能得出稳定的估计。

youdao

We estimate relatively stable international market shares for these products in the years ahead.

FORBES: Pepsi Pours On Upside Potental With Russia Deal, Coke Looks Too Expensive

The number of people newly infected has remained relatively stable since the late 1990s, and the more accurate estimate does not change that, the CDC said.

CNN: CDC: More Americans HIV-positive than previously believed

On one United Nations estimate, to keep today's worker-pensioner ratio stable till 2050, France would have to import 1.8m people a year.

ECONOMIST: France, race and immigration