Steps in Developing a Sampling Plan (5) Advantages of Disadvantages of probability samples probability samples The researcher can be sure of They are more expensive than obtaining information from a nonprobability samples of the representative cross section of the sample size in most cases. The population of interest rules for selection increase interviewing costs and professional Sampling error can be computed time must be spent in developing the sample design The survey results are projectable to the total population Probability samples take more time to design and execute than non probability samples
Steps in Developing a Sampling Plan （5） Advantages of probability samples Disadvantages of probability samples - The researcher can be sure of obtaining information from a representative cross section of the population of interest. - Sampling error can be computed. - The survey results are projectable to the total population. - They are more expensive than nonprobability samples of the sample size in most cases. The rules for selection increase interviewing costs and professional time must be spent in developing the sample design. - Probability samples take more time to design and execute than nonprobability samples
Steps in Developing a Sampling Plan (6) Advantages of Disadvantages of nonprobability samples nonprobability samples Nonprobability samples cost less Sampling error cannot be computed than probability samples. This characteristic of nonprobability The researcher does not know the samples may have considerable degree to which the sample is appeal in those situations where representative of the population accuracy is not of critical from which it was drawn mportance The results of nonprobability Nonprobability samples ordinarily samples cannot and should not be can be conducted more quickly projected to the total population than probability samples
Steps in Developing a Sampling Plan （6） Advantages of nonprobability samples Disadvantages of nonprobability samples - Nonprobability samples cost less than probability samples. This characteristic of nonprobability samples may have considerable appeal in those situations where accuracy is not of critical importance. - Nonprobability samples ordinarily can be conducted more quickly than probability samples. - Sampling error cannot be computed. - The researcher does not know the degree to which the sample is representative of the population from which it was drawn. - The results of nonprobability samples cannot and should not be projected to the total population
Steps in Developing a Sampling Plan (7) Step 5: Determine Sample Size Once the sampling method has been chosen, the next step is to determine the appropriate sample Step 6: Developing Operational Procedures for Selecting Sample Elements Involves determining whether a probability or nonprobability sample is being used
Steps in Developing a Sampling Plan （7） • Step 5: Determine Sample Size – Once the sampling method has been chosen, the next step is to determine the appropriate sample size. • Step 6: Developing Operational Procedures for Selecting Sample Elements – Involves determining whether a probability or nonprobability sample is being used
Steps in Developing a Sampling Plan (8) Step 7: Execution of the Sampling Plan The final step in the sampling process involves execution of the operational sampling plan discussed in the previous steps It is important that this step include adequate checking to make sure that specified procedures are adhered to
Steps in Developing a Sampling Plan （8） • Step 7: Execution of the Sampling Plan – The final step in the sampling process involves execution of the operational sampling plan discussed in the previous steps. – It is important that this step include adequate checking to make sure that specified procedures are adhered to
Classification of Sampling Methods 抽样方法分类 Sampling Methods Probability Samples probability Systematic Stratified Convenience Snowball Simple Cluster Judgment uota Random
Classification of Sampling Methods 抽样方法分类 Sampling Methods Probability Samples Simple Random Cluster Systematic Stratified Nonprobability Judgment Quota Convenience Snowball