Surveys Jan 21

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 Record in forecasting elections,

Summary 1.representative sample: accurate within limit of sampling error 2. non-representative sample: no reason to expect 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

Under or over-estimated 1) support for “extremist” candidates 2)Voting (vs. non-voting) 3)Support for black candidates? 4)Alcohol consumption 5)Attendance at religious services

Social Desirability bias Definition Reasons for social desirability bias – External pressure – Beliefs about self Techniques to reduce social desirability bias

Principles of Asking questions Keep them short, use everyday language Give reminders or background for less familiar or less recent issues Keep questions balanced: don’t favor one answer