非随机抽样和随机抽样的比较.pptx

Ch. 7 Selecting samples;Definition of terms;Figure 7.1 Population, sample and individual cases;1. The need to sample;2. Overview of sampling techniques;非随机抽样和随机抽样的比较 ;Figure 7.2 Sampling techniques;3. Probability sampling;Sample frame A complete list of all the cases in the population from which your sample will be drawn;How to choose the sample size?;Response rate;Population, sampling frame, samples;Select appropriate sampling technique;sampling technique;sampling technique;1. Decide on sample size: n 2. Divide frame of N individuals into n groups of k individuals: sampling fraction k=n/N 3. Randomly select one individual from the 1st group 4. Select every 1/k-th individual thereafter;sampling technique;Stratified Sample;sampling technique;;sampling technique;Overview of probability sample;Quota sampling Purposive sampling Snowball sampling Self-selection sampling Convenience sampling;4. Non-probability sampling;4. Non-probability sampling;4. Non-probability sampling;4. Non-probability sampling;4. Non-probability sampling;Selecting a non-probability sampling technique