Surveys--Sampling Aug 29

Samples and populations Need for sampling Goal: representative sample Methods of sampling – Quota Sampling – Volunteer samples – Probability (random )sampling Advantage of random sampling

Sources of error Sampling error – Relation to sample size Error from non-response – Effect in practice False answers, misunderstanding, etc.

Contemporary Issues in Sampling Cell phones Declining response rates

Summary 1.representative sample: accurate within limit of sampling error 2. non-representative sample: no expectation of accuracy, even with a big sample 3. possible to get a representative sample by “random-digit dialing” 4.declining response rates raise question whether RDD will continue to work, but so far it still seems OK