Chapter 3: Defining and Measuring Variables

What is a Construct (in Psychology)?

Hypothetical (suppose/assume) attributes or mechanisms used in theories to describe, explain, or predict behaviour.

It’s something that you can’t see or touch; it simply exists – intangible (e.g. motivation, intelligence, self-esteem, beauty, hunger, pain)

Constructs can be influenced by external stimuli and, in turn, can influence external behaviours.

What are the characteristics of a Psychological Constructs

Used as theoretical mechanisms in scientific theories (e.g., "intelligence" or "motivation").

They are systematically defined and must be operationalized using specific measurable indicators like test scores or observations.

They emphasize precision and falsifiability; if empirical evidence does not support the construct, it is revised or rejected.

What is a theory?

A set of statements about mechanisms underlying a particular behaviour.

Define Operational Definition.

A construct needs to be defined and measured, but it cannot be observed or measured directly.

That’s why researchers operationalize the construct.

Definition: The procedures (set of observations) used to measure the construct.

Example: Operationalizing "intelligence" as a score on an IQ test.

What are the limitations of an operational definition?

Limitation: It may not measure all of the construct or may rely on other constructs that are not part of the construct being measured.

(e.g., a maze test measuring a rat's anxiety instead of just spatial intelligence).

Construct vs. Latent Variable.

The "hidden" variable yielded by an operational definition that has statistical properties. (What our operational definition actually measures)

What is Validity of Measurement?