RESEARCH QUESTION
Is item misunderstanding on the South Oaks Gambling Screen (SOGS) responsible for the high rate of false positive classifications (i.e., the categorization of non-problem gamblers as problem gamblers) of this assessment tool?
PURPOSE
In the majority of studies on problem gambling prevalence, the SOGS is used to measure the rate of problem gambling in the population. However, the accuracy of the SOGS has been called into question; the SOGS tends to overestimate the prevalence of problem gambling. It has been proposed that some items on the SOGS may be misunderstood by respondents, although there is weak evidence to support this claim. The purpose of this study was to determine whether clarifying SOGS items would affect scores.
EXPERIMENT 1
HYPOTHESIS
Using clinical and nonclinical gamblers, clarification of the SOGS items would have a significant effect on SOGS scores and the effect would be the same for both samples.
PARTICIPANTS
Nonclinical sample. A total of 127 introductory psychology course students who had gambled at least three times in the preceding 12 months (60 males, 67 females, average age 19). None of the participants had previously completed the SOGS or had any prior treatment for gambling problems. Clinical sample. A total of 63 pathological gamblers from four gambling treatment programs (41 males, 22 females, average age 37). All of the participants had met the DSM-IV criteria for pathological gambling with 5% previously completing the SOGS.
PROCEDURE
Participants from both samples were randomly assigned to one of five conditions. Condition 1 was a control group: participants completed the SOGS, either the Sensation Seeking Scale (SSS; for nonclinical participants) or a clinical interview (for clinical participants), and the SOGS again. In conditions 2 and 3, participants completed the SOGS, then another SOGS with either verbal or written clarification. In conditions 4 and 5, participants completed only one SOGS with verbal or written clarification provided before administration.
MAIN OUTCOME MEASURES
The SOGS was used to assess the presence of pathological gambling in the past year. It is a 20-item, self-administered questionnaire. Respondents who score five or higher are classified as problem gamblers. The SSS was used as a distracting filler task to separate first and second administrations of the SOGS in the nonclinical sample. It also a self-administered scale.
KEY RESULTS
Nonclinical sample. Verbal clarification before administration of the SOGS resulted in a higher average SOGS score. Written clarification decreased SOGS scores and verbal clarification increased SOGS scores when clarification was provided before a single or second administration of the SOGS.
Clinical sample. Unlike the nonclinical sample, there were no significant effects of clarification across the testing conditions, however, clarification did produce more frequent change in responses than repeated testing alone (i.e., 18 of the 25 participants in clarification conditions changed responses between first and second SOGS administration compared to only 3 in the control condition).
LIMITATIONS
SOGS questions were verbally presented to participants in the verbal clarification conditions but not in the written clarification conditions; the differential effects of verbal and written clarification could be a result of procedural differences rather than the means of clarification.
CONCLUSION Experiment 2 was designed to confirm the finding of Experiment 1 that verbal clarification increases SOGS scores.
EXPERIMENT 2
HYPOTHESIS
Verbal clarification of the SOGS items would produce higher SOGS scores than verbal presentation of the SOGS without clarification.
PARTICIPANTS
A total of 48 introductory psychology course students who had gambled at least three times in the preceding 12 months (14 males, 34 females, average age 19). None of the participants had participated in Experiment 1 or had previously completed the SOGS or had any prior treatment for gambling problems.
PROCEDURE
Participants were randomly assigned to one of two conditions including: (1) verbal clarification of the SOGS items followed by administration of the SOGS; and (2) verbal presentation of the SOGS without clarification followed by administration of the SOGS.
MAIN OUTCOME MEASURE
The SOGS was used to assess the presence of pathological gambling for the past year.
KEY RESULTS
As in Experiment 1, verbal clarification of SOGS items produced higher scores than verbal presentation of the SOGS without clarification.
LIMITATIONS
The small size and nonclinical nature of the samples used in the study may limit the generalizability of the findings.
CONCLUSIONS
Clarification of SOGS items only affected SOGS scores in a nonclinical sample. This raises concern about the accuracy of the SOGS in estimating the prevalence of problem gambling in the general population. Verbal clarification was found to increase SOGS scores (thereby increasing the likelihood that non-problem gamblers would be wrongly classified as problem gamblers), which is contrary to the view that the high false positive rate of the SOGS is due to item misunderstanding. There remains a need for an accurate screen of problem gambling in the population.
