ABSTRACT
The word data is often used in very general ways-get me the data on Jones; I’m collecting data on my ancestors; we need some data to support this grant application. These uses of the word data are far too general to be useful in the context of this chapter. We will thus utilize a much more limited definition of the word. In the words of Clyde Coombs, psychometrician and author of the classic text, A Theory of Data, ‘‘Data may be viewed as relations between points in space.’’1 This use of the word data assumes a mathematical framework that makes the gathering of data, construction of data sets, and the manipulation of data much more logical and understandable, and so we will adopt that definition of data in this chapter. This chapter begins by looking at data, how it is collected and prepared for analysis. The chapter then looks at how data sets are typically structured, how data can be manipulated, changed, recalculated, and so on. Later, the chapter looks at the advantages and disadvantages of using precollected, archived data rather than collecting data for oneself. And last, the chapter looks at ways that data can be reformatted, recalculated, and otherwise changed to fit the user’s needs.
