According to Dr. Joseph Hulihan of Temple University, ice cream pain, also known as "brain freeze", is the most common form of head pain, occurring in one third of a randomly selectedpopulation.
Control villages resembling project villages in terms of population size were randomly selected from an area enclosed by two ellipses centred around, but not including, the project area.
从由两个椭圆围绕封闭而成的区域中随机抽取与项目村庄拥有类似人口规模的对照村庄，但不包括项目区域。
3
Results may not be representative of the population because of small Numbers of people, who are not likely to be randomly selected.