The Practice of Research in Criminology and Criminal Justice Ch 3

Ch 3 Conceptualization and Measurement

In chapter 3 of The Practice of Research in Criminology and Criminal Justice there are four areas of focus. They are concepts, measurement operations, evaluation of measures, and levels of measurement. We are going to address conceptualization by using substance abuse and related ideas as examples. For measurement, let us review first how measures of substance abuse have been created, utilizing procedures as available data, questions, observations, and less direct and prominent measures. We will also explain how to assess the validity and reliability of these measures. Finally, the level of measurement reflected in unrelated measures is our last topic. Hopefully, at the end of this you will have a fine comprehension of measurement.

A concept is a mental image tat summarizes a set of similar observations, feelings, or ideas. "Concepts such as substance-free housing require an explicit definition before they are used in research because we cannot be certain that all readers will share the same definition. It is even more important to define concepts such as poverty or social control or strain, we cannot be certain that others know exactly what we mean." The meaning of concepts is often disputed among experts and illuminating the meaning of such concepts does not simply benefit those unfamiliar with them. In order to do ample work of conceptualization, we need more than just a definition, for our concepts. We will probably have to distinguish inner aspects of the concept. Conceptualization is defined as "The process of specifying what we mean by a term. In deductive research, conceptualization helps to translate portions of an abstract theory into testable hypotheses involving specific variables. In inductive research, conceptualization is an important part of the process used to make sense of related observations (pp.63-64)." Obviously, without conceptualization our research in criminology would be completely different and almost certainly less efficient.

Our book defines measurement validity as "The type of validity that is achieved when a measure measures what we think it measures." No really, that's what it says. For an example of measurement validity imagine you are trying to measure delinquency, which is a pretty broad concept, and your measure of it is five questions that ask only about fighting and violence. This measure would fail to be "content" valid because it does not measure the full range of the construct of delinquency. If the items not only failed to cover the entire concept, but also don't seem to assess delinquency at all, then the measure would fail on prima facie grounds, which is Latin for "on the face" or "at first sight." So far, we have discussed two of the four types of validity that you are responsible for, content and face validity. The basic idea of these validating strategies is that measurements should look like they measure what they a supposed to measure. To make this call the researcher has to have a pretty good idea of what the underlying construct is that he or she is supposed to measure. Accordingly, it is important to have a very clear and fully developed conceptualization of the construct. If your conceptualization is vague you've got problems from the very beginning (68-70).

There are four levels of measurement: nominal, ordinal, interval, and ratio. Levels of measurement is defined as; "The complexity of the mathematical means that can be used to express the relationship between a variable's values. The nominal level of measurement, which is qualitative, has no mathematical interpretation; the quantitative levels of measurement are progressively more complex mathematically." The first of the levels is ordinal. At this level, the numbers assigned to cases specify only the order of the cases, permitting greater-than and less-than distinctions; absolute mathematical distinctions cannot be made between categories. An interval-level measure is created by a scale that has fixed measurement units but no absolute, or fixed, zero point. The numbers can be added and subtracted, but ratios are not meaningful, the values must be mutually exclusive and exhaustive. The numbers indicating the values of a variable at the ratio level of measurement represent fixed measuring units and an absolute zero point. Ratio numbers can be added and subtracted, and because the numbers begin at an absolute zero point, they can be multiplied and divides. An important thing to remember is that researchers choose levels of measurement in the process of operationalizing the variables; the level of measurement is not inherent in the variable itself (78-82).

Always remember