Moreover, the estimated rate of effective reticence, rq , is the same as it was in the basic model. Consistent with the intuition given above, however, we find a higher proportion of reticent respondents, with r= 0.82 , as opposed to r= 0.74 in the basic model.

More generally, for , given guilt and reticence rates, the average number of "Yes" responses on the CQ will be lower if the correlation between reticence and guilt is positive, i.e. if ε> 0 . This is because reticent behavior is now more likely among those respondents who otherwise would have answered "Yes", the unprincipled individuals (who have done the sensitive act). The average number of "Yes" responses on the RRQ battery is a weighted average of the responses of principled and unprincipled individuals. Unprincipled individuals are always guilty and are reticent with probability +ε . The first term in Equation (10) is thus 1 −p times the average response on the RRQ in Equation (4), but with g= 1 and replacing r by r+ ε . Similarly, principled individuals are never guilty, and also are reticent with probability r−ε , and so the second term in Equation (10) is p times Equation (4), but setting g= 0 and replacing r with r−ε .

In the remaining columns of Table 7 we impose alternative values of ε , which governs the correlation between guilt and reticence. In columns (2) and (3) we consider values of ε= 0.2 and ε= 0.4 , corresponding to successively stronger correlations between reticence and guilt. The main effect of this change is to substantially decrease our estimate of the proportion of principled individuals, which falls from p= 0.63 in the baseline to p= 0.34 when ε= 0.4 . This of course implies an increase in the estimated proportion of guilty individuals, to 1 −p= 0.66 . This figure is substantially higher than the corresponding estimate of g= 0.37 in the basic model in Table 2. The intuition for this increase is straightforward: if guilt and reticence are positively correlated then more of the "No" responses that we observe in the data are coming from individuals who did in fact do the sensitive act in question. Thus for a given observed rate of "No" responses, the proportion of unprincipled respondents in the data must be higher than in the case where reticence and guilt are assumed to be independent across respondents.

If on the other hand we assume that guilt and reticence are negatively correlated, we obtain the opposite finding. Under this assumption, "Yes" responses are more likely to signal actual guilt, since unprincipled respondents are assumed to be more likely to be willing to admit to having done sensitive acts. In this case, for a given observed rate of "Yes" responses, we must conclude that the proportion of unprincipled respondents is lower than under the benchmark where guilt and reticence are independent. This can be seen in column (4) of Table 7, where ε= −0.1 . However, in this case we also find that the estimated proportion of reticent respondents becomes implausibly high. In column (4) the proportion of principled respondents who are reticent, r−ε , is 0.88 −(−0.1) = 0.98 , with the implication that essentially all principled respondents are reticent.<sup>14</sup> Given that this conclusion is absurd, we think the case where reticence and guilt are positively correlated is much more likely to characterize the Peruvian observations.

> 14 In fact, if we go to values of ε= −0.2 or lower, we find that the estimated proportion of principled and reticent respondents, r−ε , becomes greater than one, which is in the inadmissible region of the parameter space.

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