第十一章抽样：设计与步骤

1、赵冬阳 讲师经济与管理学院市场营销博士生e-mail: 11-1Chapter ElevenSampling: Design And Procedures第十一章第十一章 抽样抽样：设计与步骤：设计与步骤Chapter Objectives学习目标区分样本与普查，并了解使用样本相对于普查的优势讨论抽样设计过程，包括定义目标总体、确定抽样框架、选择抽样技术、确定样本量、执行抽样过程将抽样技术分为非概率抽样技术与概率抽样技术描述非概率抽样技术中的便利抽样、判断抽样、配额抽样以及滚雪球抽样Chapter Objectives学习目标描述概率抽样技术中的简单随机抽样、系统抽样、分层抽样以及整群抽样了解

2、在什么条件下非概率抽样相对于概率抽样更具优势理解抽样设计过程以及抽样技术在国际市场营销研究中的应用识别与抽样设计过程有关的伦理道德问题以及如何使用适当的抽样技术解释因特网和计算机在样本设计中的使用Chapter Outline学习内容1.概要2.样本还是普查3.抽样设计过程4.抽样技术的分类5.在非概率抽样和概率抽样间抉择6.非概率抽样和概率抽样的使用7.国际市场营销研究8.市场营销研究道德9.因特网和计算机的应用10.小结样本还是普查比较项目比较项目适用条件样本普查预算小大可用时间短长总体规模大小特征差异小大抽样误差的成本低高非抽样误差的成本高低测量的性质破坏性非破坏性对个体案例的关注是否表

3、11-1The Sampling Design ProcessFig. 11.1Define the PopulationDetermine the Sampling FrameSelect Sampling Technique(s)Determine the Sample SizeExecute the Sampling Process抽样设计过程定义目定义目标总体标总体确定抽确定抽样框架样框架选择抽选择抽样技术样技术确定样确定样本量本量执行抽执行抽样过程样过程图11-1定义目标总体抽样设计从定义目标总体开始。抽样设计从定义目标总体开始。目标总体指的是拥有研究人员所目标总体指的是拥有研究人员

4、所要寻找的信息的个体或物体的集要寻找的信息的个体或物体的集合，推论就是由这些信息得出的。合，推论就是由这些信息得出的。目标总体应该根据目标总体应该根据 个体个体 抽样单位抽样单位 范围范围 时间来定义。时间来定义。 是这样一个物体，关于它的信息或是这样一个物体，关于它的信息或者来自它的信息是我们想要的。者来自它的信息是我们想要的。个体个体 单位指的是在抽样过程中的某一阶单位指的是在抽样过程中的某一阶段可供选择的个体，或者包含这个段可供选择的个体，或者包含这个个体的单位。个体的单位。抽样抽样 指的是地理边界，时间因素指的是指的是地理边界，时间因素指的是调研的时间周期调研的时间周期范围范围Defi

5、ne The Target Population定义目标总体确定样本量时重要的定性因素包括：决策的重要性研究的性质变量的数目分析的性质类似研究所使用的样本量发生率完成率资源约束Sample Sizes Used in Marketing Research StudiesTable 11.2表11-2 营销研究使用的样本量研究类型研究类型最小量最小量典型的范围典型的范围问题鉴别研究（例如市场潜力）50010002500问题解决研究200300500产品测试200300500试销研究200300500电视/广播/印刷品广告（每个被测试的广告）150200300试销市场审计10家商店1020家商店专

6、题组6组1015组Classification Of Sampling TechniquesSampling Techniques Nonprobability Sampling TechniquesConvenience SamplingJudgmental SamplingQuota SamplingSnowball SamplingProbability Sampling TechniquesSimple Random SamplingSystematic SamplingStratified SamplingCluster SamplingOther Sampling Techniqu

7、esFig. 11.2抽样技术分类抽样技术抽样技术 非概率抽样非概率抽样便利抽样便利抽样判断抽样判断抽样配额抽样配额抽样滚雪球抽样滚雪球抽样概率抽样概率抽样简单随机抽样简单随机抽样系统抽样系统抽样分层抽样分层抽样整群抽样整群抽样其他抽样技术其他抽样技术Convenience Sampling attempts to obtain a sample of convenient elements. Often, respondents are selected because they happen to be in the right place at the right time. Conve

8、nience samplingUse of students, and members of social organizationsMall intercept interviews without qualifying the respondentsDepartment stores using charge account lists“People on the street” interviews便利抽样 试图获取一个便利个体的样本，对抽样单位的选择主要由访谈人员完成，通常被访问者由于碰巧在恰当的时间正处在恰当的地点而被选中。便利抽样 包括： 1.使用学生、教会成员以及社会组织的成员

9、2.对被访问者不加资格认证的商场拦截访谈 3.使用费用帐目清单确定的百货商店 4.从杂志中撕下的问卷5.街头采访便利抽样的实例A Graphical Illustration of Convenience Sampling方便方便抽样抽样的的图形化表示图形化表示法法ABCDE16111621271217223813182349141924510152025Group D happens to assemble at a convenient time and place. So all the elements in this Group are selected. The resulting

10、 sample consists of elements 16, 17, 18, 19 and 20. Note, no elements are selected from group A, B, C and E. Fig. 11.3 11.3Judgmental SamplingJudgmental sampling is a form of convenience sampling in which the population elements are selected based on the judgment of the researcher. 判断抽样是便利抽样的一种形式，即根

11、据研究人员的判断选出总体中的个体。判断抽样判断抽样的普通实例包括：1.被选来确定一种新产品潜力的试销市场。2.在工业营销研究中被选出来的采购工程师，因为他们被公认是该公司的代表3.在投票行为研究中选出的群众领袖的选区。4.法庭上所使用的专家证人5.为测试一个新的商品陈列系统而选出的百货商店。Test marketsPurchase engineers selected in industrial marketing research Bellwether precincts selected in voting behavior researchExpert witnesses used in

12、 courtGraphical Illustration of Judgmental Sampling判断抽样的判断抽样的图图示示说明说明The researcher considers groups B, C and E to be typical and convenient. Within each of these groups one or two elements are selected based on typicality and convenience. The resulting sample consists of elements 8, 10, 11, 13, and

13、 24. Note, no elements are selected from groups A and D.Fig. 11.3Quota Sampling配额抽样Quota sampling may be viewed as two-stage restricted judgmental sampling. The first stage consists of developing control categories, or quotas, of population elements. In the second stage, sample elements are selected

14、 based on convenience or judgment.Control VariablePopulation compositionSample compositionSex PercentagePercentageNumberMale 4848480Female 5252520100100100配额抽样 可以被看做两个阶段有约束的判断抽样。配额抽样 为了确定这些配额，研究人员列出相关的控制特征并确定这些特征在目标总体中的分布。 根据判断确认相关的控制特征，包括性别、年龄及种族。第一阶段是确定总体中不同类别个体的配额。第二阶段是在便利或判断的基础上选出样本个体。A Graphica

15、l Illustration of Quota Sampling配额抽样的图示说明A quota of one element from each group, A to E, is imposed. Within each group, one element is selected based on judgment or convenience. The resulting sample consists of elements 3, 6, 13, 20 and 22. Note, one element is selected from each column or group. Fi

16、g. 11.3Snowball Sampling滚雪球抽样In snowball sampling, an initial group of respondents is selected, usually at random. After being interviewed, these respondents are asked to identify others who belong to the target population of interest. Subsequent respondents are selected based on the referrals.在雪球抽样

17、，一个初步组的受访者被选择，常常不定点地。 在访谈之后要求这些被访谈者推荐一些属于目标总体的其他人，然后运用同样的方法推荐选出后面的被访者。A Graphical Illustration of Snowball Sampling滚雪球抽样的图示说明 Elements 2 and 9 are selected randomly from groups A and B. Element 2 refers elements 12 and 13. Element 9 refers element 18. The resulting sample consists of elements 2, 9,

18、12, 13, and 18. Note, there are no elements from group E.RandomSelection ReferralsFig. 11.3Simple Random Sampling简单随机抽样给予总体中的每一个个体一个已知且相等的抽中概率每个规定了规模（n）的样本都有一个已知且相等的被实际选为样本的概率这意味着每个个体是独立于其他所有个体而被选择的Each element in the population has a known and equal probability of selection. Each possible sample of

19、 a given size (n) has a known and equal probability of being the sample actually selected. This implies that every element is selected independently of every other element.A Graphical Illustration of Simple Random Sampling简单随机抽样的图形说明（SRS）Select five random numbers from 1 to 25. The resulting sample

20、consists of population elements 3, 7, 9, 16, and 24. Note, there is no element from Group C. Fig. 11.4Systematic Sampling系统抽样The sample is chosen by selecting a random starting point and then picking every ith element in succession from the sampling frame. The sampling interval, i, is determined by

21、dividing the population size N by the sample size n and rounding to the nearest integer. When the ordering of the elements is related to the characteristic of interest, systematic sampling increases the representativeness of the sample.系统抽样通过选择一个随机的起点，然后从抽样框架中连续地每隔i个个体挑选出一个，从而选出样本。通过将总体N除以样本量n并将结果四舍

22、五入到最近的整数，可以确定出抽样间距i。当个体的顺序与需要研究的特征有关时，系统抽样能够增加样本的代表性。Systematic SamplingIf the ordering of the elements produces a cyclical pattern, systematic sampling may decrease the representativeness of the sample. For example, there are 100,000 elements in the population and a sample of 1,000 is desired. In t

23、his case the sampling interval, i, is 100. A random number between 1 and 100 is selected. If, for example, this number is 23, the sample consists of elements 23, 123, 223, 323, 423, 523, and so on. 当个体的顺序与需要研究的特征无关时，系统抽样能够降低样本的代表性。例如，总体中有100,000个个体，想要抽取一个样本量为1000的样本，此时抽样间距i为100。在1到100之间选出一个随机数如23，该样

24、本就由个体23、123、223、323、423、523、等组成。A Graphical Illustration of Systematic Sampling系统抽样图示说明Select a random number between 1 and 5, say 2. The resulting sample consists of population 2, (2+5=) 7, (2+5x2=) 12, (2+5x3=)17, and (2+5x4=) 22. Note, all the elements are selected from a single row.Fig. 11.4Stra

25、tified Sampling分层抽样A two-step process in which the population is partitioned into subpopulations, or strata. The strata should be mutually exclusive and collectively exhaustive in that every population element should be assigned to one and only one stratum and no population elements should be omitte

26、d. 分层抽样是一个两阶段过程，总体被分割为子总体，或称“层”。各层应该相互独立，并且全体上没有遗漏，因为每个总体个体都应该被分配到一层，并且只分配到一层，且不应该遗漏任何总体个体。Stratified Sampling分层抽样Next, elements are selected from each stratum by a random procedure, usually SRS. A major objective of stratified sampling is to increase precision without increasing cost.接下来，用一种随机的方法，通

27、常是SRS，从每层中选出个体。分层抽样的一个主要目的是在不增加成本的同时增加精确度。与配额抽样的区别在于样本的个体是按概率抽取的，而不是基于便利或判断。Stratified Sampling分层抽样The elements within a stratum should be as homogeneous as possible, but the elements in different strata should be as heterogeneous as possible. The stratification variables should also be closely rela

28、ted to the characteristic of interest. Finally, the variables should decrease the cost of the stratification process by being easy to measure and apply.一层之内的个体应该尽可能同质，但是不同层的个体应该尽可能异质。分层变量还应该与需要研究的特征紧密相关。最后，这些变量应该易于测量和应用，从而降低分层过程的成本。分层抽样在按比例分层抽样中，从每层中抽出的样本量与该层在整个总体中的相对量成比例。在非比例的分层抽样中，从每层中抽出的样本量与该层的相对

29、量成比例，且与该层所有个体当中需要研究的特征分布的标准差成比例。Cluster Sampling整群抽样The target population is first divided into mutually exclusive and collectively exhaustive subpopulations, or clusters. Then a random sample of clusters is selected, based on a probability sampling technique such as SRS. For each selected cluster,

30、either all the elements are included in the sample (one-stage) or a sample of elements is drawn probabilistically (two-stage).整群抽样首先将目标总体分为相互排斥且没有遗漏的子总体，或称群。然后根据一种概率抽样技术，如SRS，选出各群的一个随机样本。对于每个被选中的群而言，要么所有的个体都被包括进了样本，要么用概率抽样的方法抽出一个个体的样本。Cluster Sampling整群抽样Elements within a cluster should be as hetero

31、geneous as possible, but clusters themselves should be as homogeneous as possible. Ideally, each cluster should be a small-scale representation of the population. In probability proportionate to size sampling, the clusters are sampled with probability proportional to size. In the second stage, the p

32、robability of selecting a sampling unit in a selected cluster varies inversely with the size of the cluster.一个群内的个体应该尽可能地异质，但是各群之间应该尽可能地同质。理想情况下，每个群都应该是总体的一个小规模的代表。在样本大小的概率比例抽样，群被抽样同样依大小成比例的机率。在第二阶段，一个被选出的群中选出一个抽样单位的概率随着该群的大小呈相反的变化。Types of Cluster Sampling整群抽样的类型Cluster SamplingOne-Stage Sampling T

33、wo-Stage SamplingSimple Cluster SamplingProbability Proportionate to Size SamplingMultistage Sampling整群抽样单阶段抽样两阶段抽样简单的两阶段整群抽样与规模成比例 的概率抽样阶段抽样Fig 11.5Strengths and Weaknesses of Basic Sampling Techniques基本抽样技术的优缺点Procedures for Drawing Probability Samples抽取概率样本的步骤Simple Random Sampling简单随机抽样1. Select

34、 a suitable sampling frame.2. Each element is assigned a number from 1 to N (pop. size).3. Generate n (sample size) different random numbers between 1 and N.4. The numbers generated denote the elements that should be included in the sample.1.选择一个适当的抽样框架。2.给每个个体分配一个1和N（总体规模）之间的数字。3.在1和N之间生成n（样本量）个不同的

35、随机数字。4.所生成的数字代表了应该被包括进样本中的个体。Exhibit 11.1Procedures for Drawing Probability Samples抽取概率样本的步骤Systematic Sampling系统抽样1. Select a suitable sampling frame.2. Each element is assigned a number from 1 to N (pop. size).3. Determine the sampling interval i:i=N/n. If i is a fraction, round to the nearest integer.4. Select a random n