Unbiasedly estimating the total of a stigmatizing variable from a complex survey on permitting options for direct or randomized responses

Following the approach of Mangat and Singh (in J Ind Statist Assoc 32(3): 71–75, 1994) we consider estimating the population total of a sensitive variable like earning through gambling, amount of tax evaded etc. on generating sample responses allowing options for direct or randomized responses according to a specified device. Gathering two independent responses from each individual chosen according to any general sampling scheme we derive unbiased estimators for the total as well as for the variances of these estimators.