An uncomfortable yes/no question is posed to the respondents, so that one of the two answers is “embarrassing” or “sensitive”. for example, suppose we ask the “have you ever shoplifted? ” question. to provide anonymity, the following scheme is proposed. each respondent secretly flips an unfair coin (with probability 0 < p < 1/2 of landing heads). if the coin shows heads the respondent must tell the truth, and if the coin shows tails the respondent must tell the opposite of the truth. suppose we want to estimate the portion of people who shoplifted at some point in their life with accuracy of 0.5% and confidence level of 99%. use the chebyshev inequality to find how many people should be questioned to fulfill our requirement.