The Last Five Years Driver Risk Inventory-II, Reliability, Validity and Accuracy Any approach to assessment, or measurement must meet the criteria of reliability and validity. Reliability refers to an instrument's consistency of results regardless of who uses it. This means that the outcome must be objective, verifiable, and reproducible.
Validity refers to accuracy.
Psychometric principles and computer technology insures reliability, accuracy, objectivity, practicality and cost-effectiveness. The most common method of reporting inter-item reliability is with coefficient alpha. The 1999 reliability coefficient alphas for the DRI-II are presented in Table 7. The higher the alpha level the more reliable the scale is. Alphas above .85 are considered to be very reliable.