Statistical methods
This chapter provides an introduction to statistical methods with illustrative examples from public health and epidemiological research. The chapter begins by distinguishing between a study sample and a target population. It goes on to outline different methods of sampling, including probability and non-probability sampling methods. In the following section, the distributions of epidemiological variables are considered, leading on to discussion of probability distributions and statistical inference. Methods for comparing data from two or more groups are then outlined, including methods for continuous and categorical variables. Analysis of time-to-event data to evaluate survival times is then outlined. The final section of the chapter discusses the application of multivariable models to epidemiological data, including extensions of basic models to more complex data distributions. The chapter concludes by cautioning that increasing ease of access to sophisticated statistical methods may increase the risk of erroneous application. There is little substitute for consulting a qualified statistician, particularly with complex designs.