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Table 1 COSMIN definitions of domains, measurement properties, and aspects of measurement properties [18]

From: Evaluation of the psychometric properties of self-reported measures of alcohol consumption: a COSMIN systematic review

Term Definition
Domain Measurement property Aspect of a measurement property  
Reliability    The degree to which the measurement is free from measurement error
Reliability (extended definition)    The extent to which scores for patients who have not changed are the same for repeated measurement under several conditions: e.g. using different sets of items from the same health related-patient reported outcomes (HR-PRO) (internal consistency); over time (test-retest); by different persons on the same occasion (inter-rater); or by the same persons (i.e. raters or responders) on different occasions (intra-rater)
  Internal consistency   The degree of the interrelatedness among the items
  Reliability   The proportion of the total variance in the measurements which is due to ‘true’a differences between patients
  Measurement error   The systematic and random error of a patient’s score that is not attributed to true changes in the construct to be measured
Validity    The degree to which an HR-PRO instrument measures the construct(s) it purports to measure
  Content validity   The degree to which the content of an HR-PRO instrument is an adequate reflection of the construct to be measured
   Face validity The degree to which (the items of) an HR-PRO instrument indeed looks as though they are an adequate reflection of the construct to be measured
  Construct validity   The degree to which the scores of an HR-PRO instrument are consistent with hypotheses (for instance with regard to internal relationships, relationships to scores of other instruments, or differences between relevant groups) based on the assumptionthat the HRPRO instrument validly measures the construct to be measured
   Structural validity The degree to which the scores of an HR-PRO instrument are an adequate reflection of the dimensionality of the construct to be measured
   Hypotheses testing Idem construct validity
   Cross-cultural validity The degree to which the performance of the items on a translated or culturally adapted HR-PRO instrument are an adequate reflection of the performance of the items of the original version of the HR-PRO instrument
  Criterion validity   The degree to which the scores of an HR-PRO instrument are an adequate reflection of a ‘gold standard’
Responsiveness    The ability of an HR-PRO instrument to detect change over time in the construct to be measured
  Responsiveness   Idem responsiveness
Interpretabilityb    Interpretability is the degree to which one can assign qualitative meaning - that is, clinical or commonly understood connotations – to an instrument’s quantitative scores or change in scores.
  1. Table Legend: Table of definitions of psychometric properties measured by the COSMIN checklist, grouped by property (e.g. reliability, validity, responsiveness and interpretability)
  2. aThe word ‘true’ must be seen in the context of the CTT, which states that any observation is composed of two components – a true score and error associated with the observation. ‘True’ is the average score that would be obtained if the scale were given an infinite number of times. It refers only to the consistency of the score, and not to its accuracy [54]
  3. bInterpretability is not considered a measurement property, but an important characteristic of a measurement instrument