Ch. 3: Defining and Measuring Variables

Theory

In the behavioral sciences, statements about the mechanisms underlying a particular behavior

Constructs of hypothetical constructs

Hypothetical attributes or mechanisms that help explain and predict behavior in a theory. Also, known as hypothetical constructs

Operational definition

A procedure for indirectly measuring and defining a variable that cannot be observed or measured directly. An operational definition specifies a measurement procedure (a set of operations) for measuring an external, observable behavior and uses the resulting measurements as a definition and a measurement of the hypothetical construct

Validity

The degree to which the measurement process measures the variable it claims to measure

Face validity

An unscientific form of validity that concerns whether a measure superficially appears to measure what it claims to measure

Concurrent validity

The type of validity demonstrated when scores obtained from a new measure are directly related to scores obtained from a more established measure of the same variable

Predictive validity

The type of validity demonstrated when scores obtained from a measure accurately predict behavior according to a theory

Construct validity

The type of validity demonstrated when scores obtained from a measurement behave exactly the same as the variable itself. Construct validity is based on many research studies and grows gradually as each new study contributes more evidence

Convergent validity

The type of validity demonstrated by a strong relationship between the scores obtained from two different methods of measuring the same construct

Divergent validity

A type of validity demonstrated by using two different methods to measure two different constructs convergent validity then must be shown for each of the two constructs. Finally, there should be little or no relationship between the scores obtained for the two different constructs when they are measured by the same method

Reliability

The degree of stability or consistency of measurements. If the same individuals are measured under the same conditions, a reliable measurement procedure will produce identical (or nearly identical) measurements

Test-retest reliability

The type of reliablility established by comparing the scores obtained from two successive measurements of the same individuals and calculating a correlation between the two sets of scores

Parallel-forms reliability

The type of reliability established by comparing scores obtained by using two alternate versions of a measuring instrument to measure the same individuals and calculating a correlation between the two sets of scores

Inter-rater reliability

The degree of agreement between two observers who simultaneously record measurements of a behavior

Split-half reliability

A measure of reliability obtained by splitting the items on a questionnaire or test in half, computing a separate score for each half, and then measuring the degree of consistency between the two scores for a group of participants

Ceiling effect

The clustering of scores at the high end of a measurement scale, allowing little or not possibility of increases in value

Floor effect

The clustering of scores at the low end of a measurement scale, allowing little or no possibility of decreases in value; a type of range effect

Experimenter bias

The influence on the findings of a study from the experimenter’s expectations about the study. Experimenter bias is a type of artifact and threatens the validity of the measurement, as well as both internal and external validity

Single-blind research

A research study in which the researcher does not know the predicted outcome for any specific participant

Double-blind research

A research study in which both the researcher and the participants are unaware of the predicted outcome for any specific participant

Demand characteristics

Any potential cues or features of a study that (1) suggests to the participants what the purpose and hypothesis are, and (2) influence the participants to respond or behave in a certain way. Demand characteristics are artifacts and can threaten the validity of the measurement, as well as both internal and external validity

Reactivity

Participants’ modification of their natural behavior in response to the fact that they are participating in a research study or the knowledge that they are being measured. Reactivity is an artifact and can threaten the validity of the measurement, as well as both internal and external validity

Good subject role

In a study, a participant’s tendency to respond in a way that is expected to corroborate the investigator’s hypothesis

Negative subject role

In a study, a participant’s tendency to respond in a way that is expected to refute the investigator’s hypothesis

Apprehensive subject role

In a study, a participant’s tendency to respond in a socially desirable fashion rather than truthfully

Faithful subject role

In a study, a participant’s attempt to follow experimental instructions to the letter and to avoid acting on the basis of any suspicions about the purpose of the experimenter

Laboratory

A research setting that is obviously devoted to the discipline of science. It can be any room or space that the subject or participant perceives as artificial

Field

Any research setting that the participant or subject perceives as a natural environment