Robert A. Cummins Australian Centre on Quality of Life Deakin University Measurement scales and depression

What are the issues under investigation? (a)The problem of sub-optimal response scales (b)The problem of sub-optimal depression sales Why are these issues important? (a)Likert scales are blunt instruments (b)We seem not to understand what depression actually is What are the implications? (a)Our response scales may be compromising our measurements (b)We may be misdiagnosing depression Overview

Freyd, M. (1923). The graphic rating scale. Journal of Educational Psychology, 14, “When you have satisfied yourself on the standing of this person in the trait on which you are rating him, place a check at the appropriate point on the horizontal line. You do not have to place your check directly above a descriptive phrase. You may place your check at any point on the line.” (p.88). For job interviews Does he appear neat or slovenly in his dress? [then standardized to 0-10]

Rensis Likert Head Survey Research Center University of Michigan Why only five levels of choice? Likert, R. (1932) A technique for the measurement of attitudes. Archives of Psychology, No.14, New York. Strongly disapprove DisapproveUndecidedApproveStrongly approve

1.People can make more than five points of discrimination. They are therefore blunt instruments, not capturing the full extent of discrimination Problem #1

Increasing the number of choice points above 5 increases scale sensitivity Diefenbach, M.A., Weinstein, N.D., & O’Reilly, J. (1993). Scales for assessing perceptions of health hazard susceptibility. Health Education Research, 8, Russell, C., & Bobko, P. (1992). Moderated regression analysis and Likert scales: Too coarse for comfort. Journal of Applied Psychology, 77, Jaeschke, R., & Guyatt, G.H. (1990). How to develop and validate a new quality of life instrument. In: B. Spilker (Ed.) Quality of life assessment in clinical trials (pp ). New York: Raven Press.

1.People can make more than five points of discrimination. They are therefore blunt instruments 2.The number of choice points cannot easily be expanded because we do not have the necessary adjectives Problems with Likert scales

Roy Morgan Research (1993) Roy Morgan Research (1993). International values audit, 22/23 May. Melbourne: Roy Morgan Research Centre. Delighted Very pleased Pleased Mostly satisfied Mixed feelings Unhappy Mostly dissatisfied Very unhappy Terrible

1.People can make more than five points of discrimination. They are therefore blunt instruments 2.The number of choice points cannot easily be expanded because we do not have the necessary adjectives 3.The psychometric distance between the named adjectives does not accord with the interval nature of the scale Problems with Likert scales

Ware and Gandek (1994) used the Thurstone method of equal-appearing intervals to calculate the following distances between category labels used in the SF Actual psychometric separation PoorFairGood Very good Excellent Ware, J. E., & Gandek, B. (1994) The SF-36 Health Survey: Development and use in mental health research and the IQOLA project. International Journal of Mental Health, 23,

Louis Leon Thurstone ( ) Dept Psychology University of Chicago Jones, L.V., & Thurstone, L.L. (1955) The psychophysics of semantics: An experimental investigation. The Journal of Applied Psychology, 39(1),

How satisfied are you with your life as a whole? Frequency Response scale Can people reliably use 11-points of discrimination? N≈30,000

The relationship between SWB and depression Can the Subjective Wellbeing, or Positive Affect, be used as a measure of depression? Critical issue #2

Dominant Source of SWB Control Challenging conditions Set Point range SWB 50 Upper Threshold Lower Threshold No challenge Set point Homeostasis Very strong challenge Strength of challenging agent 70 Defensive range Strong homeostatic defense 80 a b c Lower Threshold

Theoretical proposition Positive wellbeing is controlled by a homeostatic process Homeostatic defeat means positive wellbeing is lost Depression is the loss of positive wellbeing The measurement of positive wellbeing should be THE measure of depression Upper Threshold Lower Threshold Strong homeostatic defense a b c Lower Threshold Loss of positive wellbeing= depression

Is this idea consistent with (DSM-IV) ? Symptoms of depression include the following: (a)depressed mood (such as feelings of sadness or emptiness) (b)reduced interest in activities that used to be enjoyed, sleep disturbances (either not being able to sleep well or sleeping to much) (c)loss of energy or a significant reduction in energy level (d)difficulty concentrating, holding a conversation, paying attention, or making decisions that used to be made fairly easily (e)suicidal thoughts or intentions.

Depression is--- (a)Loss of positive affect due to homeostatic failure (b)reduced interest (c)loss of energy (d)difficulty concentrating (e)suicidal thoughts These are just the consequential symptoms caused by the loss of positive affect

How do the measures of depression and SWB relate to each other? r ≈.7 How do we establish that loss of positive wellbeing = depression?

4.4% Frequency Percentage points of SWB How do the distributions of population incidence match? Commonwealth Department of Health and Aged Care (2000) 5.8% 1997 National Survey of Mental Health and Wellbeing 6.0% Incidence of depression in Australia

Depression scores (DASS) NormalMildModerate PWI The relationship between SWB and depression (symptoms) follows the theoretical pattern prescribed by homeostasis.

Conclusions (a)11-point end-defined scales are superior to Likert scales (b) Depression should be defined, and measured, as a loss of positive affect.