In this longitudinal study, 4, 689 Iceland residents aged 33to 65 first participated in a population study and were questionedabout frequency of headaches and symptoms.

在这个纵向研究中，有4，689名冰岛居民，年龄在33到65岁之间，首次参与到人口研究中来，进行关于频发头痛及症状的调查。

youdao

Friedman's pricing formula takes into account square footage, cleaning frequency, and "population density."

Friedman的服务价格将面积，频率，甚至“人口密度”都计算在内。

youdao

Most studies could not quantify disease frequency in the general population as they are hospital-based and confounded by variations in threshold and the rate of hospitalization.

多数研究不能把一般人群当中的发病频率给予定量是因为它们是基于医院的并且被混杂在住院率的变化之中。

youdao

But the remarkable and good news is that we have cut the frequency of tornado fatalities, in deaths per million population, by at least fourfold in the past century.

FORBES: The Great Tornadoes Of 2011 Put In Perspective

Population growth and migration from western Europe may have driven up the frequency of people carrying haplogroup H.

BBC: Making of Europe unlocked by DNA

Voter fraud currently seems to occur with greatest frequency in a few populous states, like California, where a large illegal population and a notorious Motor Voter registration law create great potential for mischief, and in big cities with powerful political machines, like Chicago, Detroit, and St.

FORBES: Fixing National Elections: Will Tuesday's Voting Be Honest, or Marred By Fraud?