Compensatory and non-compensatory multidimensional randomized item response models.

Randomized response (RR) models are often used for analysing univariate randomized response data and measuring population prevalence of sensitive behaviours. There is much empirical support for the belief that RR methods improve the cooperation of the respondents. Recently, RR models have been extended to measure individual unidimensional behaviour. An extension of this modelling framework is proposed to measure compensatory or non-compensatory multiple sensitive factors underlying the randomized item response process. A confirmatory multidimensional randomized item response theory model (MRIRT) is proposed for the analysis of multivariate RR data by modelling the response process and specifying structural relationships between sensitive behaviours and background information. A Markov chain Monte Carlo algorithm is developed to estimate simultaneously the parameters of the MRIRT model. The model extension enables the computation of individual true item response probabilities, estimates of individuals' sensitive behaviour on different domains, and their relationships with background variables. An MRIRT analysis is presented of data from a college alcohol problem scale, measuring alcohol-related socio-emotional and community problems, and alcohol expectancy questionnaire, measuring alcohol-related sexual enhancement expectancies. Students were interviewed via direct or RR questioning. Scores of alcohol-related problems and expectancies are significantly higher for the group of students questioned using the RR technique. Alcohol-related problems and sexual enhancement expectancies are positively moderately correlated and vary differently across gender and universities.