@@ -54,7 +54,7 @@ These design probabilities in turn can be used to compute the conditional probab
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$$
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\text{Pr}(A|r)=\frac{\pi_A \text{Pr}(r|A)}{\pi_A \text{Pr}(r|A)+ (1-\pi_A) \text{Pr}(r|A^{'})}
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- $$ (eq:one)
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+ $$ (eq:util-rand- one)
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## Zoo of Concepts
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\text{or}&\\
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\text{Pr}(A^{'}|r)&>1-\pi_A
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\end{aligned}
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- $$ (eq:two)
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+ $$ (eq:util-rand- two)
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From Bayes's rule:
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$$
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\frac{\text{Pr}(A|r)}{\text{Pr}(A^{'}|r)}\times \frac{(1-\pi_A)}{\pi_A} = \frac{\text{Pr}(r|A)}{\text{Pr}(r|A^{'})}
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- $$ (eq:three)
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+ $$ (eq:util-rand- three)
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If this expression is greater (less) than unity, it follows that r is jeopardizing with respect to $A$($A^{'}$). Then, the natural measure of jeopardy will be:
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@@ -87,7 +87,7 @@ g(r|A)&=\frac{\text{Pr}(r|A)}{\text{Pr}(r|A^{'})}\\
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&\text{and}\\
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g(r|A^{'})&=\frac{\text{Pr}(r|A^{'})}{\text{Pr}(r|A)}
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\end{aligned}
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- $$ (eq:four)
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+ $$ (eq:util-rand- four)
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Suppose, without loss of generality, that $\text{Pr}(\text{yes}|A)>\text{Pr}(\text{yes}|A^{'})$, then a yes (no) answer is jeopardizing with respect $A$($A^{'}$), that is,
@@ -126,7 +126,7 @@ For that reason, Lanke (1976) {cite}`lanke1976degree` argued that ah appropriat
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$$
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\max \left\{ \text{Pr}(A|\text{yes}) , \text{Pr}(A|\text{no}) \right\}
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- $$ (eq:five)
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+ $$ (eq:util-rand- five-a )
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Holding this measure constant, he explained under what conditions the smallest variance of the estimate was achieved with the unrelated question model or Warner's (1965) original model.
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@@ -138,7 +138,7 @@ They measured "private protection" as
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$$
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\frac{1-\max \left\{ \text{Pr}(A|\text{yes}) , \text{Pr}(A|\text{no}) \right\} }{1-\pi_A}
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- $$ (eq:six)
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+ $$ (eq:util-rand- six)
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### 2.4 Greenberg, Kuebler, Abernathy, and Horvitz (1977)
@@ -151,27 +151,27 @@ They defined the hazard for an individual in $A$ as the probability that he or s
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$$
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\text{Pr}(\text{yes}|A)\times \text{Pr}(A|\text{yes})+\text{Pr}(\text{no}|A)\times \text{Pr}(A|\text{no})
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- $$ (eq:seven-a)
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+ $$ (eq:util-rand- seven-a)
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Similarly, the hazard for an individual who does not belong to $A$ would be
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$$
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\text{Pr}(\text{yes}|A^{'})\times \text{Pr}(A|\text{yes})+\text{Pr}(\text{no}|A^{'}) \times \text{Pr}(A|\text{no})
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- $$ (eq:seven-b)
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+ $$ (eq:util-rand- seven-b)
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Greenberg et al. (1977) also considered an alternative related measure of hazard that "is likely to be closer to the actual concern felt by a respondent."
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The "limited hazard" for an individual in $A$ and $A^{'}$ is
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$$
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\text{Pr}(\text{yes}|A)\times \text{Pr}(A|\text{yes})
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- $$ (eq:eight-a)
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+ $$ (eq:util-rand- eight-a)
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and
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$$
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\text{Pr}(\text{yes}|A^{'})\times \text{Pr}(A|\text{yes})
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- $$ (eq:eight-b)
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+ $$ (eq:util-rand- eight-b)
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This measure is just the first term in $(7)$, i.e., the probability that an individual answers "yes" and is perceived to belong to A.
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@@ -210,28 +210,28 @@ Then there is an $r_i$ such that
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$$
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\frac{\partial U_i\left(\text{Pr}(A|r_i),\phi_i\right) }{\partial \text{Pr}(A|r_i)} <0, \text{ for } \phi_i \in \left\{ \text{truth},\text{lie}\right\}
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- $$ (eq:nine-a)
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+ $$ (eq:util-rand- nine-a)
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and
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$$
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U_i\left(\text{Pr}(A|r_i),\text{truth}\right)>U_i\left(\text{Pr}(A|r_i),\text{lie}\right) , \text{ for } \text{Pr}(A|r_i) \in [ 0,1]
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- $$ (eq:nine-b)
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+ $$ (eq:util-rand- nine-b)
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Suppose now that correct answer for individual $i$ is "yes".
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Individual $i$ would choose to answer truthfully if
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$$
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U_i\left(\text{Pr}(A|\text{yes}),\text{truth}\right)\geq U_i\left(\text{Pr}(A|\text{no}),\text{lie}\right)
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- $$ (eq:ten-a)
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+ $$ (eq:util-rand- ten-a)
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If the correct answer is "no," individual $i$ would volunteer the correct answer only if
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$$
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U_i\left(\text{Pr}(A|\text{no}),\text{truth}\right)\geq U_i\left(\text{Pr}(A|\text{yes}),\text{lie}\right)
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- $$ (eq:ten-b)
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+ $$ (eq:util-rand- ten-b)
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Assume that
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@@ -249,15 +249,15 @@ At equality, constraint $(10.\text{a})$ determines conditional probabilities t
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$$
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U_i\left(\text{Pr}(A|\text{yes}),\text{truth}\right)= U_i\left(\text{Pr}(A|\text{no}),\text{lie}\right)
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- $$ (eq:eleven)
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+ $$ (eq:util-rand- eleven)
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Equation $(11)$ defines a "truth border".
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Differentiating $(11)$ with respect to the conditional probabilities shows that the truth border has a positive slope in the space of conditional probabilities:
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$$
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\frac{\partial \text{Pr}(A|\text{no})}{\partial \text{Pr}(A|\text{yes})}=\frac{\frac{\partial U_i\left(\text{Pr}(A|\text{yes}),\text{truth}\right) }{\partial \text{Pr}(A|\text{yes})}}{\frac{\partial U_i\left(\text{Pr}(A|\text{no}),\text{lie}\right) }{\partial \text{Pr}(A|\text{no})}}>0
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- $$ (eq:twelve)
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+ $$ (eq:util-rand- twelve)
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The source of the positive relationship is:
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V(\text{Pr}(A|\text{yes}) , \text{Pr}(A|\text{no}))
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= &\frac{{\pi_A}^2 (1-\pi_A)^2}{n}\times \frac{1}{\text{Pr}(A|\text{yes})-\pi_A}\times \frac{1}{\pi_A-\text{Pr}(A|\text{no})}
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\end{aligned}
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- $$ (eq:thirteen)
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+ $$ (eq:util-rand- thirteen)
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where the random sample with replacement consists of $n$ individuals.
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@@ -360,11 +360,11 @@ The following inequalities restrict the shapes of iso-variance curves:
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$$
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\frac{d \text{ Pr}(A|\text{no})}{d\text{ Pr}(A|\text{yes})}\bigg|_ {\text{constant variance}}=\frac{\pi_A-\text{Pr}(A|\text{no})}{\text{Pr}(A|\text{yes})-\pi_A}>0
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- $$ (eq:fourteen-a)
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+ $$ (eq:util-rand- fourteen-a)
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$$
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\frac{d^2 \text{ Pr}(A|\text{no})}{d\text{ Pr}(A|\text{yes})^2}\bigg|_ {\text{constant variance}}=- \frac{2 \left[ \pi_A-\text{Pr}(A|\text{no})\right] }{\left[ \text{Pr}(A|\text{yes})-\pi_A \right] ^2}<0
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- $$ (eq:fourteen-b)
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+ $$ (eq:util-rand- fourteen-b)
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From expression $(13)$ and $(14)$ we can see that:
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@@ -477,7 +477,7 @@ Lanke (1976) recommends a privacy protection criterion that minimizes:
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$$
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\max \left\{ \text{Pr}(A|\text{yes}) , \text{Pr}(A|\text{no}) \right\}
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- $$ (eq:five)
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+ $$ (eq:util-rand- five-b )
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Following Lanke's suggestion, the statistician should find the highest possible $\text{ Pr}(A|\text{yes})$ consistent with truth telling while $\text{ Pr}(A|\text{no})$ is fixed at 0. The variance is then minimized at point $X$ in Figure 3.
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@@ -615,27 +615,27 @@ Greenberg et al. (1977) defined the hazard for an individual in $A$ as the proba
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$$
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\text{Pr}(\text{yes}|A)\times \text{Pr}(A|\text{yes})+\text{Pr}(\text{no}|A)\times \text{Pr}(A|\text{no})
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- $$ (eq:seven-a )
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+ $$ (eq:util-rand- seven-aa )
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The hazard for an individual who does not belong to $A$ is
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$$
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\text{Pr}(\text{yes}|A^{'})\times \text{Pr}(A|\text{yes})+\text{Pr}(\text{no}|A^{'}) \times \text{Pr}(A|\text{no})
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- $$ (eq:seven-a )
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+ $$ (eq:util-rand- seven-bb )
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They also considered an alternative related measure of hazard that they said "is likely to be closer to the actual concern felt by a respondent."
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Their "limited hazard" for an individual in $A$ and $A^{'}$ is
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$$
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\text{Pr}(\text{yes}|A)\times \text{Pr}(A|\text{yes})
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- $$ (eq:eight-a )
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+ $$ (eq:util-rand- eight-aa )
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and
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$$
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\text{Pr}(\text{yes}|A^{'})\times \text{Pr}(A|\text{yes})
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- $$ (eq:eight-b )
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+ $$ (eq:util-rand- eight-bb )
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According to Greenberg et al. (1977), a respondent commits himself or herself to answer truthfully on the basis of a probability in $(7)$ or $(8)$ **before** randomly selecting the question to be answered.
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