Psychological Measurement

  • To answer any psychological question, first people need to be measured
    • Psychometrics
    • Quantify psychological phenomena
  • Commonly done through psychological tests or questionnaires
    • Persons answer questions which can be rated or scored
  • Can be administered in several ways:
    • Administer the test to a lot of persons once
      • Cross-sectional
    • Administer the test to the same person multiple times
      • Repeated measures / longitudinal data
    • Administer the test to multiple people multiple times
      • Multi-level designs

Cross-sectional Analysis

Psychological Tests

Psychological Questionnaires

Macroscopic Behavior

  • Consistently in most Psychological tests and questionnaires, item scores correlate positively with each-other
    • A child who answers one summation item correctly is likely to answer another correctly
    • Someone who "does a thorough job" tends not to "be lazy"
  • These positive correlations are classically modeled by having the items be the causal result of some latent factor
    • Intelligence
    • Depression
    • Neuroticism
  • The correlation between any pair of items is modeled as being solely due to the common influence of the latent trait
    • Local independence
  • The field of psychometrics is, mostly, devoted to measuring such latent traits such that they can be used in psychological experiments, growth modeling, scoring/examination, etc.