ABSTRACT
Sampling is a key issue in education research; much research stands or falls on the sampling. Sampling decisions may determine the nature, reliability, validity, credibility, trustworthiness, utility and generalizability of the data collected, and indeed how to collect such data. This chapter provides comprehensive advice on sampling issues and practices (how to ‘do’ sampling), including: key considerations and decisions in sampling; sample size; statistical power and sample size; confidence levels and intervals; sampling and data types; sampling with data analysis in mind; sampling error; population characteristics and representativeness; access to the sample; sampling strategies; types of probability and non-probability samples; the importance of random sampling, where possible; sampling qualitative research and mixed methods research; and planning a sampling strategy. It notes that there are occasions when intended and actual sampling may differ as accommodation has to be found between what is desirable and what is possible. Samples must be fit for: purposes; timescales and constraints on the research; the research design; the methods of data collection; and the methodology of the research.
