CLINICAL MEASUREMENT IN CARDIOLOGY - VALI DITY AND MEASUREMENT ERROR

Measurements represent an essential part of clinical activity. Very of ten, however, relevant disagreement in clinical measurements becomes a pparent. The sources of this variability are the subjects (patients) t hat are measured, the measurement instrument itself, and the observer. The assessment of the quality of measurement usually relies on the ev aluation of its reproducibility and its validity. The reproducibility Is basically measured as the inter-observer concordance, the intra-obs erver concordance, and the test-retest concordance. The specific param eter used to its quantification (intra-class correlation coefficient, kappa index, graphic methods, etc.) depend on the kind of variable to be measured. The validity of the measurement is the degree to which th e measurement is really measuring what we think it should. Dan accepta ble standard is available, then so called criterion validity is usuall y assessed. Otherwise the validity should be assessed by other ways th at use subjective criteria (content validity and face validity) or emp irical criteria (construct validity).