商务统计

一
1.Statistic is a body of principles and methods concerned with extracting
useful information from a set of data to help people make decisions. 2.Descriptive statistics deals with methods of organizing, summarizing
and presenting data ina a convenient and informative form.
3.Inferential statistics is a body of methods for drawing conclusions
about characteristics of a population,based on information available in a sample taken from the population.
4.A populationg is the group of all items of interest in a statistical
problem.
5.A descriptive measure of a population is called a parameter.
6.A sample is a subset of data drawn from the population.
7.A descriptive measure of a sample is called a statistic.
8.Statistical inference is the process of making an estimate,forecast or
decision about a population parameter,based on the sample data.
9.Descriptive statistics including graphical techniques and numerical
techniques.
10.Statistics can be subdivided into two basic areas :descriptive statistics
and inferential statistics.
二
1. A variable is some characteristic of a population or sample.
2. Data are observed values of a variable.
3. There are three types of data:
numerical(quantitative),normal(categorical or qualitative) and ordinal(ranked) data.
4. Frequency distribution---an agreement or table that groups data into
non-overlapping intervals called classes, which cover the complete range of observations ,and records the number of observations in each class.
5. p51
6. 制作茎叶图的步骤（the step of developing a stem-and-leaf）
The first step in developing the display is to decide how to split each observation into two parts;we next list the stems in a column from smallest to largest.
7. The advantage and disadvantage of a stem-and-leaf display?
The advantage of having the leaves arranged in order of magnitude is that,The disadvantage is that it is more troublesome to do the arranging.
8. A stem-and-leaf display and histogram 区别：
A stem-and-leaf display is similar to a histogram turned on its side,but
the display holds the advantage of retaining the original observations.Moreover,because the stems are listed in order of size ,the middle observations can be determined fairly easily.
On the other hand，a histogram can readily accommodate a large number of observations，can display relative frequencies，and can be
adapted more easily to changes in the classes used.
三、p146
9. Empirical rule(经验准则就是3r准则)
(1)Approxiately 68%of all observations fall within one standard
devation of the mean.
(2) Approxiately 95%of all observations fall within two standard
devation of the mean.
(3) Approxiately 99.7%of all observations fall within three standard
devation of the mean.
10. Random experiment(随机事件)
A random experiment is a process that results in one of a number of
possible outcomes,which cannot be predicted with certainly.
11.Sample space(样本空间)
A sample space of a random experiment is a list of all possible outcomes
of the experiment ,the outcomes listed must be both mutually exclusive and axhaustive.
12.Simple events(elementary events)简单事件或基本事件
The individual outcomes in a sample space are also called simple events or elementary events.
plement(补集)
The complement of any event A ,denote as A,is the set of all outcomes in the sample space S that do not belong to A.
14.Event（事件）
An event is any collection of one or more possible outcomes from an experiment..
15.Intersection(交集)
The intersection of any two events A and B ,denoted as A B,is the joint event consisting of all outcomes common to both Aand B.
16.Union(并集)
The union of any wo events A and B, denoted as A B,is the event consisting of all outcomes in A or in B or in both.。