In marking your work, your tutor will look at: - whether the sampling population, sampling frame and sampling unit are appropriately defined in relation to the research aims and concepts employed - the extent to which you demonstrate understanding of the various sampling techniques and their uses - the extent to which you demonstrate an understanding of any limitations of particular techniques - the clarity with which you explain your selection of a particular technique. Sampling Terminology 1. Population: in sampling the term ‘population has a very specific meaning Figure 4.1 Sampling Process Theory/hypothesis Practical issues Sampling methods General Universe Working Universe Sample Source: Adapted from Yates, S. (1998) Issues in Social Research, Milton Keynes: Open University p.18 2. Sampling frames 3. Random or probability sampling 4. Non-probability Sampling 5. quota sampling, Sample Design Issues The aims of the research project 1. Data analysis PROBABILITY OR NON-PROBABILITY SAMPLING? Probability or Random Sampling Simple random sampling Stratified random sampling Systematic random sampling Multi-stage cluster sampling Non Random or Non-Probability Sampling Convenience Sampling Purposive sampling Problems of non-response Sample size Absolute and relative sample size Resources Non-response Heterogeneity of the population Data analysis Response rates The response rate can be calculated by: Response rate = Number of Responses /over/ Number eligible to respond Acceptable response rates Guidelines for promoting response rate and minimising response bias • Use trained interviewers. • Quality Assurance system in place • Identify larger number of eligible respondents than needed – use if necessary • Use surveys only when respondents are interested in topic • Keep responses confidential and anonymous • Follow up mail/telephone surveys • Provide incentives • Be realistic about eligibility criteria. Anticipate proportion who may not be able to participate e.g. incorrect addresses (Fink, A., 1995) Limits to generalisation