工程方法_6 sigma_13.概率分布.ppt

Probability Distributions概率分布;Learning Objectives学习目的;As we progress from description of data towards inference of data, an important concept is the idea of a probability distribution. 当我们从描述性数据进步到推论性数据时,一个重要的内容就是概率分布的概念. To appreciate the notion of a probability distribution, we need to review various fundamental concepts related to it: 为了解概率分布的概念, 我们需要复习各种基本相关概念: Experiment, Sample Space, Event 实验,样本空间,事件 Random Variable 随机变量.;Experiment实验 An experiment is any activity that generates a set of data, which may be numerical or not numerical. 实验是产生一系列数据的行为,数据有可能是数字的或非数字的. ;Random Experiment 随机实验 If we throw the dice again and again, or produce many shafts from the same process, the outcomes will generally be different, and cannot be predicted in advance with total certainty. 如果我们掷子一次由一次,或从相同工序生产许多轴,结果会是不同的.不能完全提前预测. An experiment which can result in different outcomes, even though it is repeated in the same manner every time, is called a random experiment. 一个实验导致不同的结果,即使它是每次以相同方式,这叫做随机实验 ;Sample Space样本空间 The collection of all possible outcomes of an experiment is called its sample space.收集实验的所有可能结果称为样本空间 Event事件 An outcome, or a set of outcomes, from a random experiment is called an event, i.e. it is a subset of the sample space. 一个结果,或一套结果,从一个随机实验出来的称为事件,也就是样本空间的子集;Event事件 Example例 1: Some events from tossing of a dice.从掷骰子的一些事件. Event 事件1: the outcome is an odd number 结果是奇数 Event事件 2: the outcome is a number 4 大于4的结果 Example例 2: Some events from measuring shaft ?:从测量轴径的一些事件 Event事件 1: the outcome is a diameter mean直径大于平均值 Event 事件2: the outcome is a part failing specs.未通过规格的结果.;Random Variable随机变量 From a same experiment, different events can be derived depending on which aspects of the experiment we consider important. 从一个相同的实验, 由于我们认为重要的实验方面不同而产生不同的结果 In many cases, it is useful and convenient to define the aspect of the experiment we are interested in by denoting the event of interest with a symbol (usually an uppercase letter), e.g.: 许多方面,它是很有用和方便的