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 governmental units (state 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.

Descriptive statistics 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 difficulties for the unaided human mind. This general class of problems characteristically involve 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 entire district could be estimated fairly accurately from a 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.

统计学

统计方法的早期发展受到两种截然不同的影响。 统计学有一个"母亲"，她致力于井井有条地记录政府机构的文件(国家和统计学这两个词源于同一个拉丁语词根，status)，还有一 个有绅士般的赌博"父亲"，他依靠数学来提高赌技，以便在几率的游戏中取胜。 "母亲"对其子女统计学的影响表现在计数、测量、描述、制表、归类和人口普查。 所有这些导致了 现代描述统计学的诞生。

由于"父亲"的影响则产生了完全基于概率论原理的现代推理统计 学。 描述统计学涉及对所收集数据的制表、制图和描述。 这些数据可以是数量性的数据，如高度、智商、或者是层级性的数据--具有连续性的变量--或数据也可以代表性质变量，如 性别、大学专业或性格类型等等。

数量庞大的数据通常必须经过概括或删减的程序才能为 人所理解。 描述统计学就是这样一个工具，它对极其庞杂的数据进行描述、概括或删减，使其变成能为人理解的东西。 推理统计学是一套已定形了的方法体系，它解决的是光凭人 脑极难解决的另一类问题。

这类问题的显著特点是试图通过取样调查来作出预测。 例如， 有一位教育督察想知道在一个庞大的学校系统中，不吃早饭就上学的学生、已经做过防感冒免疫的学生，或其它任何类型的学生占多大比例。 若具备一些统计学的知识，这位督察应 明白，询问每个孩子是没有必要而且没有效率的，只要用100 个孩子为样本，他就可以相当 精确地得出这些孩子占整个学区的比例了。 因此，推理统计学的目的就是通过了解一个群体中一些样本的特性，从而对整个群体的特性进行推测和估算。

Obtaining Fresh Water from Icebergs

The concept of obtaining fresh water from icebergs that are towed to populated areas and arid regions of the world was once treated as a joke more appropriate to cartoons than real life. But now it is being considered quite seriously by many nations, especially since scientists have warned that the human race will outgrow its fresh water supply faster than it runs out of food.Glaciers are a possible source of fresh water that has been overlooked until recently. Three-quarters of the Earth’s fresh water supply is still tied up in glacial ice, a reservoir of untapped fresh water so immense that it could sustain all the rivers of the world for 1,000 years. Floating on the oceans every year are 7,659 trillion metric tons of ice encased in 10,000 icebergs that break away from the polar ice caps, more than ninety percent of them from Antarctica.

Huge glaciers that stretch over the shallow continental shelf give birth to icebergs throughout the year. Icebergs are not like sea ice, which is formed when the sea itself freezes, rather, they are formed entirely on land, breaking off when glaciers spread over the sea. As they drift away from the polar region, icebergs sometimes move mysteriously in a direction opposite to the wind, pulled by subsurface currents. Because they melt more slowly than smaller pieces of ice, icebergs have been known to drift as far north as 35 degrees south of the equator in the Atlantic Ocean. To corral them and steer them to parts of the world where they are needed would not be too difficult.

The difficulty arises in other technical matters, such as the prevention of rapid melting in warmer climates and the funneling of fresh water to shore in great volume. But even if the icebergs lost half of their volume in towing, the water they could provide would be far cheaper than that produced by desalinization, or removing salt from water.

从冰山中获取淡水 把冰山拖到世界上人口稠密的地区和干旱地带，再从中获取淡水，这个想法曾一度被认为是一个笑话，更适合于卡通画，而非现实生活。然而现在，许多国家正相当认真地考虑 这件事情，特别是在科学家们发出警告之后。

科学家们认为人类将在耗尽粮食之前首先耗 尽淡水资源。冰川是一个直到最近以前一直被忽视的可能的淡水源。全球四分之三的淡水 还锁在冰川的冰块中。冰川就是一个蓄水池，其中未开发的淡水量是如此巨大，足够支持全世界的江河 1000 年。 每年有 7，659 万亿公吨冰漂流在海洋中。它们包含在 10，000 座从极地冰帽中断裂出来的冰山中。 这些冰山的 90%以上来自南极。 一年四季里，覆盖在浅层大陆架上的巨大冰川生成了众多冰山。 冰山和海水的冰不同，后者是海水自身结冰 形成的，而冰山则完全是在陆地上形成的。

当冰川伸展到海水中时，冰山就断裂下来。 当漂离极地地区时，冰山有时会在底层洋流的推动下颇为神秘地逆风移动。由于冰山比小块的冰融化要慢，因此有的冰山在大西洋中向北飘到了赤道以南 35°的地方。 把冰山蓄拦起 来并拖到世界上需要它们的地方将不会太困难。有困难的是其它的技术事宜。 比如，如何 防止冰山在较暖的气候中迅速融化以及如何把大量的淡水收集到岸上去。 但是，即便在拖的过程中冰山失去了一半体积，这样做也远比从海水中脱盐取得淡水便宜。