This unit deals with the gathering and analysis of data. In part of this unit, students are given the foundations of survey design with some discussion of quota sampling, question construction, common ambiguities and unintended biases, probability sampling, simple random sampling, stratified sampling, ratio and regression estimators, systematic sampling and cluster sampling. The other component of the unit is a discussion of designed experiments and will cover the following topics: the completely randomised design, randomised blocks, nested designs, random effects models and the analysis of covariance.