中央資管：范錚強 7 Types of Sampling Designs Element Selection ProbabilityNonprobability UnrestrictedSimple random Convenience 便利 RestrictedComplex random Purposive 立意 SystematicJudgment ClusterQuota Stratified Snowball Double
中央資管：范錚強 8 Steps in Sampling Design What is the target population? What are the parameters of interest? What is the sampling frame? What is the appropriate sampling method? What size sample is needed?
中央資管：范錚強 9 When to Use Larger Sample Sizes? Desired precision Number of subgroups Number of subgroups Confidence level Population variance Small error range
中央資管：范錚強 10 Simple Random Advantages Easy to implement with random dialing Disadvantages Requires list of population elements Time consuming Uses larger sample sizes Produces larger errors High cost
中央資管：范錚強 11 Systematic Advantages Simple to design Easier than simple random Easy to determine sampling distribution of mean or proportion Disadvantages Periodicity within population may skew sample and results Trends in list may bias results Moderate cost
中央資管：范錚強 12 Stratified Advantages Control of sample size in strata Increased statistical efficiency Provides data to represent and analyze subgroups Enables use of different methods in strata Disadvantages Increased error will result if subgroups are selected at different rates Especially expensive if strata on population must be created High cost
中央資管：范錚強 13 Cluster Advantages Provides an unbiased estimate of population parameters if properly done Economically more efficient than simple random Lowest cost per sample Easy to do without list Disadvantages Often lower statistical efficiency due to subgroups being homogeneous rather than heterogeneous Moderate cost
中央資管：范錚強 14 Stratified and Cluster Sampling Stratified Population divided into few subgroups Homogeneity within subgroups Heterogeneity between subgroups Choice of elements from within each subgroup Cluster Population divided into many subgroups Heterogeneity within subgroups Homogeneity between subgroups Random choice of subgroups
中央資管：范錚強 15 Nonprobability Samples Cost Feasibility Time No need to generalize Limited objectives
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