Title: Cases, variables and values
Course: UGQuants (SSPS) > Section: Introduction to Quantitative Analysis

Cases

Most quantitative data can be understood as based on three fundamental building blocks: cases, variables and values.

The Case

A ‘case’ is a concept that is common to many approaches in social and political research, not just quantitative analysis. One way of understanding a case is that it is the thing or things that we have data for or about. We might also describe cases as our ‘units of analysis’. The ways in which a case or cases are selected are always important in any research approach. For example, in a case study we usually select only one case in which we have a particular interest, often because we believe it has the capacity to tell us something about some wider phenomenon. So, in a case study our ‘case’ might be a school, hospital or political party.

Or, e.g., if our research aim involves the collection of qualitative data from a particular group of people, we often choose to carry out a number of interviews designed to allow people to respond to questions in their own terms. Typically, this involves selection of a relatively limited number of cases (often somewhere between about 10 and 100) which all meet some criterion related to our research aims: e.g. parents of children under 5 years old; members of the Scottish National Party; refugees.

1 | Cases are always multiple: a key element of quantitative analysis is comparison, therefore it follows that we need more than one case to compare.
2 | Cases are almost invariably numerous: it is possible to conduct quantitative analysis with, e.g., less than 100 cases but more often we analyse hundreds or thousands of cases.
3 | While the basis of selection of cases may be that we want only to analyse a specific category of people or thing, often we want to select a broad and diverse range of people or things representing a sample of cases from a larger population to which they belong. We usually want to use our selected cases (our sample) to help us reach conclusions about the wider population to which they belong. This is discussed further in the sections on sampling and inference. However, sometimes we are able to include all cases in a given population.
4 | Most commonly, our cases are individuals. When this is true we often describe our data as micro data, and those individuals who provide the data as respondents. This is often produced from the responses to questionnaires, which you will probably have experienced, either through self-completion (e.g. pen and paper or online) or an interviewer asking questions with fixed responses (e.g. in person or on the telephone). But our cases might also be households, publications (e.g. political manifestos) or even entire countries. When our cases are very large entities like countries, we often describe our data as macro or aggregate data. This means that the data are drawn together not from the responses of one individual or household, but from many different sources. This distinction will become clearer when we understand the nature of variables.