Inference 1: Chance, bias, and confounding

Inference describes the process of deriving conclusions from observations to generalizations and is a key activity in all research. This chapter commences with considering how the findings from a research sample can be applied to the population from which that sample was drawn—that is, the role of chance in accounting for observed findings, and the possibility that they might have arisen because of errors in the design of the study (bias)—whether relating to the people in the sample (selection bias) or the measurements applied (information bias). The chapter then begins to consider the extent to which a causal relationship can be inferred from an observed association, by considering the role of confounding factors as alternative explanations and ways in which these are addressed in statistical analyses.