Sample also called Subsample, were drawn from the overall part of acollectionof individuals.Sample of each individual called the Specimen,samples contained inthe specimen number is called the sample size,also called samplesize, also called sample capacity . commonly used nTodeterminethequality ofthesample characteristicstheproceedsfrom the data Is called the sample values, also called sample dataWhenthe numberof samples is more,theanalysisresult ismuch closerto the total value. : samples representative of the overall is better.sample2007.426
2007.4 26 sample Sample also called Subsample, were drawn from the overall part of a collection of individuals 。 Sample of each individual called the Specimen , samples contained in the specimen number is called the sample size ， also called sample size ， also called sample capacity ， commonly used n 。 To determine the quality of the sample characteristics ， the proceeds from the data Is called the sample values ， also called sample data When the number of samples is more, the analysis result is much closer to the total value. ， samples representative of the overall is better
: Random sampling（typical: Stratified samplingsampling)(Equidistant: Systematic samplingsampling) Cluster sampling2007.46Sampling method27
2007.4 27 Sampling method • Random sampling • Stratified sampling（typical sampling） • Systematic sampling（Equidistant sampling） • Cluster sampling
Random samplingRefers to each individual of the population has theequal chance of being drawn。This sampling methodcan't considerdrawingwhich sampleinadvancecompletely by chance,and ensure the representativesamplesamplingWhen the population capacity is not big,randomsamplingis an effectivemethod of sampling2007.4Sampling method28
2007.4 28 Sampling method Random sampling Refers to each individual of the population has the equal chance of being drawn。This sampling method can't consider drawing which sample in advance, completely by chance, and ensure the representative sample。 sampling When the population capacity is not big, random sampling is an effective method of sampling
Stratified samplingStratified samplingisto classifyor stratify populationaccording tothe main factors closely related to the researchcontent,Then draw sample according to the random principleat each layer。 Stratified sampling can reduce differences inthe layer,increase the representation of the sample。samplingsampleWhen the data is not uniform, stratified sampling is aneffectiyemethodofsampling2007.4Sampling method29
2007.4 29 Sampling method Stratified sampling Stratified sampling is to classify or stratify population according to the main factors closely related to the research content ,Then draw sample according to the random principle at each layer。 Stratified sampling can reduce differences in the layer, increase the representation of the sample。 sampling sample When the data is not uniform，stratified sampling is an effective method of sampling
Stratified sampling (add)Fordesigningtodeterminehowto distributethe samplesize in the various types of groups, usually has the following threemethods:1 ) Equal distribution: for each various types ,distribute the same number of units:2 ) Proportional distribution : according to theproportion of each type of group in the population todistribute sample unit number;3)Optimal distribution:the comprehensive of 1)and 2);2007.46Sampling method30
2007.4 30 Stratified sampling（add） For designing to determine how to distribute the sample size in the various types of groups, usually has the following three methods： １）Equal distribution: for each various types , distribute the same number of units; ２）Proportional distribution : according to the proportion of each type of group in the population to distribute sample unit number; ３） Optimal distribution: the comprehensive of 1) and 2); Sampling method