A Beginner’s Guide to Psychological Assessments
Learn how psychological assessments work and what their results can tell you.
What Is a Psychological Scale?
A psychological scale measures aspects of how we think, feel, or behave using a defined set of questions and scoring rules. People often call it a test or questionnaire; in professional settings, it is an assessment tool.
A well-developed scale goes through a standardized development process and is tested for reliability and validity. This helps it provide a more objective picture of someone’s psychological state, traits, or possible difficulties than an informal questionnaire can.
Common Scale Formats
Likert Scale
A common format that asks how much you agree with a statement. Responses usually run from “strongly disagree” to “strongly agree,” with intermediate choices such as “unsure.”
Semantic Differential
You describe your attitude toward something by choosing a position between opposite adjectives, such as good–bad, strong–weak, or fast–slow. These pairs can capture qualities, strength, or activity.
Rating Scale
Often used in clinical assessments, this format asks you to rate how frequent or severe a symptom is. Choices might include none, mild, moderate, moderately severe, and severe.
Who Provides the Answers?
You answer questions about your own experience. This approach is common in assessments of personality, mood, and attitudes.
Someone who knows the person provides the ratings. This is useful when assessing children, when a person cannot describe their own experience, or when answers may be influenced by a desire to appear socially acceptable.
What Makes a Good Scale?
Psychometrics—the study of psychological measurement—uses reliability and validity to evaluate the quality of an assessment.
Reliability
Reliability concerns consistency and stability. A scale is more reliable when it gives similar results for the same person under comparable conditions over time. Cronbach’s alpha is one commonly used reliability measure.
Validity
Validity concerns whether a scale measures what it is intended to measure. It is central to deciding whether an assessment is useful for its stated purpose.
Further reading
Scores, patterns and common misreadings, explained in plain language.
SDS, BDI, CES-D, HADS, SCL-90 and GDS-15 compared by length, focus, and best fit.
Ishihara plates, the number 74, and what red, blue, yellow, and green mean.
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