Is validity of measures no simple matter?
It is important to consider the definition and validity of the construct at issue as well as the adequacy of its representation in the measurement instrument. By considering a particular construct within the context of a conceptual model, researchers and clinicians will improve their understanding of the construct's validity as measured.
Mortality was high among patients admitted from the wards to ICU; many were inpatients for days or weeks before admission. The longer these patients were in hospital before ICU admission, the higher their mortality. Patients with delayed admission differed in some respects compared to those admitted earlier.