Scales are ordinarily constructed with the principle of unidimensionality which means the items that make up the scale, represent a single characteristic of a construct, and implementing the scale results in one number which represents the level of severity of the construct being assessed. For example, on the BDI-FastScreen, depression is rated between 0 and 21, representing no depressive symptoms and severe major depressive disorders respectively (Hennessey & Palone, 2003). The HADS rates users on a scale between 0 and 21, representing normal and severe anxiety/depression respectively (Campbell, 2007).
When social scientists construct scales and indexes, it is important that they assess validity and reliability, just as they would for any assessment. For example, the scale must be compared to other data that measures the same construct, contemporary research regarding the construct, and to other assessments of the same construct. The scales and indexes are correlated with other measures. These correlations attest to the instrument's validity. For example, the Hospital Anxiety and Depression Scale (HADS) was correlated to a 5-point psychiatric rating scales of anxiety and depression with 100 medical outpatients (Campbell, 2007). The Beck Depression Inventory Fast Screen for Medical Patients (BDI-FastScreen) was correlated with the Hospital Anxiety and Depression scales. Scales allow researchers to rank items by intensity, and changes ordinal and nominal data to interval level scales, which alleviates the limitations of nominal and ordinal data.
The samples upon which norms are based determines the generalizeability of the measure. A scale must be normed on a variety of populations to determine the extent the scale is reliable and valid in those populations. The BDI Fast-Screen was normed on 268 individuals drawn from four clinical environments. All were from the Philadelphia area. The norms for this assessment do not suggest generalizeability to other populations without further research (Hennessey & Pallone, 2003). That said, the BDI-FastScreen has been utilized with a variety of individuals, including patients with multiple sclerosis (Benedict, Fishman, McClellan, Bakshi, & Weinstock-Guttman, 2003), geriatric patients (Scheinthal, Steer, Giffin, & Beck, 2001), patients with chronic pain (Poole, Bramwell, & Murphy (2009) and cancer patients (Alacacıoğlu, Öztop, & Yılmaz, 2012). It may be safe to say that the BDI-FastScreen is generalizeable to a variety of medical patients, but not to individuals without medical conditions.
The authors of HADS list no information regarding norms in the manual, so it would be difficult to determine for which populations this scale would be appropriate, based on the manual alone. Additional research has been completed on adolescent populations, although without further research, this scale does not appear generalizeable to other populations. It has been developed to assess depression, anxiety, and irritability that results from medical conditions (Martin, 2007). This may be the only population for which the scale is reliable and valid.
Alacacıoğlu, A., Öztop, İ., & Yılmaz, U. (2012). The Effect of Anxiety and Depression on Quality of Life in Turkish Non Small Lung Cancer Patients. Turk Toraks Dergisi / Turkish Thoracic Journal, 13(2), 50-55. doi:10.5152/ttd.2012.12
Campbell, M., H. (2007). Test review of the Hospital Anxiety and Depression Scale with theIrritability-Depression-Anxiety Scale and the Leeds Situational Anxiety Scale. In K. F. Geisinger, R. A. Spies, J. F. Carlson, & B. S. Plake (Eds.), The seventeenth mental measurements yearbook. Retrieved from the Burros Institute's Mental Measurements Yearbook online database.
Hennessy, J., J. & Pallone, N., J. (2003). Review of the BDI-FastScreen for Medical Patients. In B.S. Plake, J.C. Impara, & R.A. Spies (Eds.), The seventeenth mental measurements yearbook. Lincoln, NE: Buros Institute of Mental Measurements. Retrieved from http://web.ebscohost.com.ezp.waldenulibrary.org/
Martin, W., E. (2007). Test review of the Hospital Anxiety and Depression Scale with theIrritability-Depression-Anxiety Scale and the Leeds Situational Anxiety Scale. In K. F. Geisinger, R. A. Spies, J. F. Carlson, & B. S. Plake (Eds.), The seventeenth mental measurements yearbook. Retrieved from the Burros Institute's Mental Measurements Yearbook online database.
Poole, H., Bramwell, R., & Murphy, P. (2009). The utility of the Beck Depression Inventory Fast Screen (BDI-FS) in a pain clinic population. European Journal of Pain, 13(8), 865-869. doi: 10.1016/j.ejpain.2008.09.017
Scheinthal, S. M., Steer, R. A., Giffin, L., & Beck, A. T. (2001). Evaluating geriatric medical outpatients with the Beck Depression Inventory-FastScreen for Medical Patients. Aging & Mental Health, 5(2), 143-148. doi: 10.1080/13607860120038320
Whiston, S., C. & Eder, K. (2003). Review of the BDI-FastScreen for Medical Patients. In B.S. Plake, J.C. Impara, & R.A. Spies (Eds.), The seventeenth mental measurements yearbook. Lincoln, NE: Buros Institute of Mental Measurements. Retrieved from http://web.ebscohost.com.ezp.waldenulibrary.org/