1 External validity: Sampling

So far, you have learnt to ask a RQ, identify different ways of obtaining data, and design the study.

In this chapter, you will learn how to obtain the sample to study. You will learn to:

distinguish, and explain, precision and accuracy.
distinguish between random and non-random sampling.
select random samples.
identify and describe why random samples are preferred over non-random samples.
identify, describe and use simple random sampling.
identify, describe and use systematic sampling.
identify, describe and use stratified sampling.
identify, describe and use cluster sampling.
identify, describe and use multistage sampling.
identify ways of obtaining samples that are more likely to be representative samples.