A modified randomization device for Warner’s model
In the present study, a modification of Warner’s (1965) randomized response procedure is considered. For this case, the modified estimator of ... [Pi Greek], the proportion of the population belonging to sensitive group, is shown to be unbiased and always more efficient than the Warner’s estimator.
Under certain conditions, this estimator is also more efficient than the estimator proposed by Mangat et al. (1995)