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Objective Measurement of Subjective Phenomena

3. The Construct, or Characteristic, to be Measured

When measuring behavioral outcomes in the social sciences, the personal characteristic to be assessed is called a construct (Cronbach & Meehl, 1955; Messick, 1995). The construct is a proposed attribute of a person that often cannot be measured directly, but can be assessed using a number of indicators or manifest variables.

Constructs are also discussed under other labels, such as theoretical constructs or latent variables, which are interchangeable terms.

Ease of Measurement

Constructs vary in their ease of measurement, with some constructs being relatively easy to assess and others requiring more subtle or indirect measurement.

Direct:

Some attributes or constructs can be measured directly. In medical settings, direct measurements are often obtained on routine doctor visits.

Example 1

Direct construct examples:

  1. Height (in inches or cm)
  2. Weight (in lbs or kg)
  3. Blood pressure (in mmHg)

Indirect:

In the behavioral and social sciences, we usually must use more indirect ways to measure constructs, so we develop a number of items to assess the construct.

Example 2

Indirect construct examples:

  1. Depression - Scales for depression often consist of 10 to 20 items or more, and the score for depression is a sum of scores on these items.
  2. Happiness - Happiness is a narrower construct than depression, but a happiness scale might still require 5 to 10 items or more to assess well.

Note: Ease or directness of measurement is not an indicator of how closely related a scale score is to an underlying construct or how important the attribute is for a given problem.

Messick, S. (1995). Validity of psychological assessment: Validation of inferences from persons’ responses and performances as scientific inquiry into score meaning. American Psychologist, 50, 741-749.