In this chapter, we have learnt about writing and understanding research questions. Research questions (RQs) are always about an outcome (O) in some population. Some RQs have a comparison or connection (C), and some also have an intervention (I). RQs may be estimation-type RQs or decision-type RQs.
The outcome numerically summarises the population or subsets of the population (so is usually worded in terms of percentages, averages, etc.), but the data comes from individuals in the population by measuring, observing or assessing the response (or dependent) variable. Similarly, the data concerning the comparison or connection comes from measuring or observing the explanatory (or independent) variables.
The who or what that observations are made from are called the units of observation. The smallest independent units (that is, units with very little in common) are called the units of analysis.
The following short video may help explain some of these concepts: