ABSTRACT
This chapter is an introduction to the language and concepts of measurement in social science. It looks at how people are selected for study in psychological research. One of the major tasks in attempting to assess psychological variables is often the move from categorical variable. Very few psychological research projects have ever drawn a truly random sample from a large population. In a simple random sample every case in the target population has an equal chance of selection and so does every possible combination of cases. If the authors require a simple random sample, say, 20 employees from the 500 at Wizzo Fireworks in Neasden, then they must take all employees names and use one of the first three methods. In a systematic random sample they select every n'th case from the population, where n is any number.
