统计(Statistics)

　　there were two widely divergent influences on the early development of statistical methods. statistics had a mother who was dedicated to keeping orderly records of government units (states and statistics come from the same latin root status) and a gentlemanly gambling father who relied on mathematics to increase his skill at playing the odds in games of chance.

　　the influence of the mother on the offspring, statistics, is represented by counting, measuring, describing, tabulating, ordering, and the taking of censuses-all of which led to modern descriptive statistics. from the influence of the father came modern inferential statistics, which is based squarely on theories of probability.

　　describing collections involves tabulating, depicting and describing collections of data. these data may be quantitative such as measures of height, intelligence or grade level------variables that are characterized by an underlying continuum---or the data may represent qualitative variables, such as sex, college major or personality type.

　　large masses of data must generally undergo a process of summarization or reduction before they are comprehensible. descriptive statistics is a tool for describing or summarizing or reducing to comprehensible form the properties of an otherwise unwieldy mass of data.

　　inferential statistics is a formalized body of methods for solving another class of problems that present great of problems characteristically involves attempts to make predictions using a sample of observations. for example, a school superintendent wishes to determine the proportion of children in a large school system who come to school without breakfast, have been vaccinated for flu, or whatever.

　　having a little knowledge of statistics, the superintendent would know that it is unnecessary and inefficient to question each child: the proportion for the sample of as few as 100 children. thus , the purpose of inferential statistics is to predict or estimate characteristics of a population from a knowledge of the characteristics of only a sample of the population.

推荐阅读：

　　英语作文 我的旅行

　　法律对儿童成长的必要调整(Law Adjustment for Children＇s Maturity A Necessity or Redundancy?)

　　冰山获得淡水(Obtaining Fresh water from icebergs)

　　请环境保护的英语作文

　　我的爱好英语作文五篇

　　有关热气球的英语作文