1. Opinion polls and survey research

2. What do surveys do? Measure concepts –Provide indicators for concepts Allow us track opinion and test theories

3. Types of studies Cross-sectional data –One point in time Longitudinal cross-sectional data –Sometimes allows us to distinguish between aging effects and cohort effects Cohort analysis –allows us follow individuals much more closely

4. Sample survey process Define the population to be learnt about –‘sample frame’? Sample the population Decide on the type of survey Design the questionnaire –Existing measure –Pre test Administer the survey Analyse the results

5. Sampling What do we want to generalise to? –Theoretical population –Unit of analysis? What population do we sample from? –Sampling frame Who is in the study? –The sample

6. Types of samples Simple random sample –Probability sampling Stratified random sample Multistage random sample (cluster) Convenience Snowball Quota

7. Central Limit Theorem – Example Here we have a distribution of means, as the (n) basis of the mean increases the results tend toward the centre, and become ‘normal’. When we have normally distributed data statistical inference is possible and our certainty that the estimate is accurate increases When n increases: The distributions becomes more and more ‘normal’ The spread of the distributions decreases

8. Population versus sample Sample Population

9. Problems of polling Sampling error –Sampling (random) error is the ‘luck of the draw’ –So for a party about 40%, and a sample of 1000, it will be ±3% –But for a much smaller party, say 5% it will be ± 1.4%

10. Problems of polling Error –Sampling (random) error Non-sampling (systematic) error –Selection bias Do we systematically exclude some types of people? –Non-response bias Those who respond are different –Response bias e.g. Questions on sensitive subjects – i.e. support for Sinn Féin used to be; views on race, immigration etc.

11. Opinion polls results in year to last GE

12. The pitfall of surveys Biased questions Difficult questions –Reluctance to answer honestly Asking too much of the respondent –The respondent may not know why they act the way they do Using attitudes when we want/ mean behaviour

13. Pitfalls of surveys II Multi-dimensional questions Assuming what you mean to find out Wordiness Biased samples

14. Alternatives Surveys versus revealed preferences Measure ‘pace of life’ by looking at average walking speeds in a city Measure ‘happiness’ by looking at incidence of mental disorders –Why good? –Aggregate? –But different mental health regimes

15. Tomorrow’s debate Opinion polls should be banned during election campaigns For: Cathal Ó Fainín Against: Eoin O’Sullivan