20 Questions of Gamblers Anonymous: A Psychometric Study with Population of Spain.

The authors present a psychometric study of the questionnaire proposed by the Gamblers Anonymous organization for the self-assessment of problem gambling. The study was carried out in Spain with two samples: one of 127 problem gamblers (mean age: 41.67; sex: 78.7% men; mean duration of the problem: 5 years) and the other of 142 social gamblers (mean age: 38.46; sex: 60% men). The questionnaire was self-applied, in the presence of one of the investigators in case any doubts arose. The results indicate that it is a good screening instrument, with high reliability (Cronbach's alpha = 0.94), good covergent validity (the correlation with the SOGS questionnaire is high (r = 0.94; p < 0.001)), good factorial validity (the questionnaire's structure is unidimensional and coherent (just one factor explains more than 50% of the variance)), and its discriminative power is high (diagnostic efficacy = 98.88%). The study offers a comparative analysis of this instrument with other measures of problem gambling, emphasizing its extraordinary performance.