"These targets are set for 2015 and are to achieve at least 90 percent measles vaccination coverage nationally and 80 percent coverage in every district, reduce measles cases to less than five per million population, reduce measles mortality by U.N.health agencies have made huge strides in reducing the number of children dying from measles.

VOA: standard.2010.05.21

They divide by n-1 to make it an unbiased estimator of the population variance, but I'm just going to show it in a simple way here.

当除以n-1表示的是对总体的,无偏估计,我在这里只是说的简单一点

耶鲁公开课 - 金融市场课程节选

The U.N.Fund for Population Activity says more than 600,000 African women already suffer from obstetric fistula with as many as 30,000 new cases each year.

VOA: standard.2009.12.23

Yahya Kane is a program specialist with the U.N.Fund for Population Activity.

VOA: standard.2009.12.23