Concepts are used at all stages of research. Research topics or questions are expressed in terms of concepts; so are hypotheses and conclusions.Think back to the Sudan Fertility Survey. The conclusions were expressed in concepts: one was that fertility, a concept, declined as the education of women, another concept, increased. Generalizations are also expressed in concepts. The conclusion we just cited from the Sudan Fertility Survey is also accepted as a broad generalization because so many studies found the same result.

Concepts, however, cannot be observed directly. As we said, they are abstractions that exist only as mental images of things we want to talk about. To do research, we have to convert concepts to things we can observe. We do this by defining concepts in terms of measurable variables.

Variables

Variables represent concepts. Like concepts, variables are defined in words, but, as used in social research, variables have a special characteristic. Variables have two or more observable forms or values. In short, they vary. Any condition or aspect of social behavior or social life that has at least two conditions or amounts of something is a variable.

In the previous chapter, we described several variables central to the Sudan Fertility Survey. These included fertility and education. Each could and did vary from zero to some number. Variables to which we can assign numbers are known as quantitative variables. A few examples of quantitative variables include your age, your height, your intelligence, your family's income, or the number of students at your university. Other variables exist in terms of qualities or categories rather than in terms of numbers. Gender is a variable with only two (the minimum) categories - male and female. Other examples of categorical or qualitative variables are social class, which is often described as "high," "middle," or ""low;" occupation, which can be expressed in various categories as "farmer," "merchant," "official" and so on; or marital status, commonly described as "single," "married," "divorced," "separated," or "widowed." Once you think about it, you will see all kinds of quantitative and qualitative variables.

Attributes of variables

The values or categories making up a variable are its attributes. Attributes are what social scientists measure to describe a variable. It is easy to mix up the name of a variable with its attributes. Box 3.1 illustrates the attributes for a few variables.

To summarize, attributes are the observable characteristics of variable; variables are the logical combinations of attributes. Male and female, for example, are the attributes of the variable we call gender. The numbers of persons in a household, from 1 to perhaps 20 or more, represent the attributes of the variable, household.

Box 3.1 Some variables and their attributes
Variable	Attributes
Gender	Male, female
Nationality	Sudanese, Zambian, Egyptian, etc.
Intelligence	120, 97, 111, 105
Your major	Management, psychology, chemistry
Family size	4, 12, 6, 10, 2
Social status	Low, middle, high

For another way of describing variables and their attributes, take a look at Variables.