Chapter 3 Constructs, Variables, and Definitions.

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1 Chapter 3 Constructs, Variables, and Definitions

2 Scientists operate on two levels: theory- hypothesis-construct and observation. A hypothesis, “early deprivation produces learning deficiency”, consists of two concepts, “early deprivation” and “learning deficiency”, joined by a relation word, produces. It is on the theory-hypothesis-construct level. Scientists must operate at the level of observation. They must define these constructs so that observations are possible.

3 Concepts and Constructs A concept express an abstraction formed by generalization from particulars. For example, achievement is an abstraction formed from the observation of certain behaviors of children. These behaviors are associated with the mastery or “learning” of school tasks— reading words, doing arithmetic problems, drawing pictures, and so on. The various observed behaviors are put together and expressed in a word.

4 Concepts and Constructs A construct is a concept. It has the added meaning, however, of having been deliberately and consciously invented or adopted for a special scientific purpose. For example, “intelligence” is a concept, an abstraction from the observation of presumably intelligent and nonintelligent behaviors. But as a scientific construct, “intelligence” means both more and less than it may mean as a concept. It means that scientists consciously and systematically use it in two ways: (1) it enters into theoretical schemes and is related in various way to other constructs and (2) “intelligence” is so defined and specified that it can be observed and measured.

5 Variables Scientists somewhat loosely call the constructs or properties they study “variable.” A variable is a symbol to which numerals or values are assigned. Qualitative variables: dichotomies v.s. polytomies It is always possible to convert a continuous variable to a dichotomy or a polytomy. Such conversion can serve a useful conceptual purpose, but is poor practice in the analysis of data because it discards information.

6 Constitutive and Operational Definitions of Constructs and Variables Words or constructs can be defined in two general ways. 1.defining a word by using other words, which is what a dictionary does. 2.defining a word by assigning expressed or implied actions or behaviors. This kind of definition can be called a behavioral or observational definition.

7 Constitutive and Operational Definitions of Constructs and Variables Constitutive and operational definitions A constitutive definition defines a construct using other constructs. An operational definition assigns meaning to a construct or a variable by specifying the activities or “operations” necessary to measure it and evaluate the measurement. There are, in general, two kinds of operational definitions: 1. measured, and 2. experimental.

8 Constitutive and Operational Definitions of Constructs and Variables A measured operational definition describes how a variable will be measured. An experimental operational definition spells out the details (operations) of the investigator’s manipulation of a variable. For example, reinforcement can be operationally defined by giving the details of how subjects are to be reinforced (rewarded) and not reinforced (nor rewarded) for specified behaviors.

9 Constitutive and Operational Definitions of Constructs and Variables The importance of operational definitions cannot be overemphasized. They are indispensable ingredients of scientific research because they enable researchers to measure variables and because they are bridges between the theory- hypothesis-construct level and the level of observation. There can be no scientific research without observations, and observations are impossible without clear and specific instructions on what and how to observe. Operational definitions are such instructions. Although indispensable, operational definitions yields only limited meanings of constructs.

10 Types of Variables 1.independent and dependent variables 2.active and attribute variables 3.continuous and categorical variables

11 Independent and dependent variables An independent variable is the presumed cause of the dependent variable, the presumed effect. When we say: If A, then B, we have the conditional conjunction of an independent variable (A) and a dependent variable (B). A general rule is that when the researcher manipulates a variable or assigns participants to groups according to some characteristic, that variable is the independent variable.

12 Active and Attribute Variables Manipulated variables will be called active variables; measured variables will be called attribute variables. Manipulation means, essentially, doing different things to different groups of subjects. Variables that cannot be manipulated are attribute or subject-characteristic variables. Subjects come to a study with these variables (attributes) ready-made or preexisting.

13 Active and Attribute Variables There are some studies where the independent variable could have been manipulated; however, for logistical or legal reasons, they were not. For example, comparing different care facilities’ effect on cognitive and functional measures of Alzheimer’s patients. The attribute variable was the type of facility (traditional nursing home versus special care unit). The researchers were forced to study the subjects after they had been assigned to a care facility.

14 Active and Attribute Variables Some variables that are attributes can also be active. For example, we can measure the anxiety of subjects. Anxiety is in this case obviously an attribute variable. However, we can also manipulate anxiety by inducing different degrees of anxiety. Actually, we cannot assume that the measured (attribute) and the manipulated (active) “anxieties” are the same. We may assume that both are “anxiety” in a broad sense, but they are certainly not the same.

15 Continuous and Categorical Variables A continuous variable is capable of taking on an ordered set of values within a certain range. Categorical variables belong to a kind of measurement called nominal. In nominal measurement, there are two or more subsets of the set of objects being measured. Individuals are categorized by their possession of the characteristic that defines any subset. It is an all-or-none kind of thing.

16 Continuous and Categorical Variables The expression “qualitative variable” has sometimes been applied to categorical variables, especially to dichotomies, probably in contrast to “quantitative variables” (our continuous variables). Such usage reflects a somewhat distorted notion of what variables are. They are always quantifiable, or they are not variables. If x has only two subsets and can take on only two values (1 and 0), these are still values, and the variable varies. It has been called “dummy variable”

17 Constructs, Observables, and Latent Variables We can say that constructs are nonobservables; and variables, when operationally defined, are observables. A latent variable is an unobserved “entity” presumed to underlie observed variables. The best-known example of an important latent variable is “intelligence.” We can say that three ability tests—verbal, numerical, and spatial—are positively and substantially related. We believe that something is common to the three tests or observed variables, and name this something “intelligence.” It is a latent variable.

18 Constructs, Observables, and Latent Variables When we enunciate a theory, we enunciate in part systematic relations among latent variables. We are not too interested in the relation between observed frustrated behaviors and observed aggressive behaviors, for example, though we must of course work with them at the empirical level. We are really interested in the relation between the latent variable frustration and the latent variable aggression. Another example: “motivation” is a latent variable, a construct invented to account for presumably “motivated” behavior. This means that researchers must always measure presumed indicators of motivation and not motivation itself.

19 Examples of Variations and Operational Definitions “Test” definitions, like “intelligence is defined as a score on X intelligence test,” are very specific. A definition like “frustration is prevention from reaching a goal” is more general and requires further specification to be measurable. An example on measured variable: “Intrinsic motivation” is defined operationally as ” The cumulative amount of time that each student played with the pattern blocks with the reward system absent.”

20 Examples of Variations and Operational Definitions An example on experimental variable: Here subjects are given a self-esteem test, but when they are given feedback, the information on the official-looking feedback report is bogus. Subjects of the same measured level of self- esteem are divided into three feedback groups: positive, negative, and none. In the positive feedback condition (positive self-esteem), subjects are described with statements such as “clear thinking.” Those in the negative group (negative self-esteem) are given adjectives like “passive in action.” The “no feedback” group are told that their personality profiles (self-esteem) were not ready due to a backlog in scoring and interpretation.