Valid measurement: The right instrument for the situation Select the best instrument for The construct(s) of interest A specific patient A known set of circumstances –Clinical setting –Clinical application –Time frame –Burden Scores within a valid range One or more clinical decisions –Discrimination –Prediction –Evaluation Validation coefficients Other instruments correlate –High, if comparable –Low, if different Cross-sectional –one point in time Predictive –Associated with future event Longitudinal –Subjects are stable over time –Subjects who change over time 31
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