In classical test theory an obtained score, which comprises a person's true score and error score is

"Classical test theory" is a psychometric framework for understanding and analyzing the properties of measurement instruments, such as tests and assessments, and their relationship to the underlying trait or ability being measured.

Key Points

• In classical test theory, an observed score is the score that a person actually receives on a test or assessment, which comprises both their true score (the score that reflects their actual ability or trait being measured) and their error score (the score that reflects the effects of measurement error or other extraneous factors).
• The observed score is typically used to make decisions or inferences about the person's true score or level of ability.

Additional Information

• True score represents actual ability,
• error score represents measurement error
• standard score is expressed in standard deviation units from the mean.