Research questions and hypotheses inherently provide information on data needs, in terms of what variables should be measured and with what variation (see Chapter 3). Collecting data with the desired properties requires one to:
define a target population and sample;
decide how to draw the sample; and
identify a sample size.
As with most aspects of empirical research, data collection requires that theoretical concerns (of which there are many) are weighed against practical considerations. Statisticians have developed elaborate rules, guidelines and formulae for developing sampling strategies. This formal approach to sampling is important, but in many cases individual researchers working...