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The Price of Illicit Drugs: 1981 through the - The White House

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Figure A4. Predicted Weights for Cocaine: Cocaine, <strong>1981</strong>-Q1 to 2000-Q2<br />

We fit a Poisson regression model (E(y t ) = exp( + time t ) and V(y t ) = E(y t ), where y t =<br />

emergency-events at time t) to <strong>the</strong> resulting “extended” DAWN database (18 semi-annual<br />

emergency-event counts from 1988 <strong>through</strong> 1999 for 29 cities plus <strong>the</strong> Rest <strong>of</strong> U.S.) to obtain<br />

modeled counts for <strong>the</strong> 78 quarters from Q1 <strong>1981</strong> <strong>through</strong> Q2 2000 for each city. <strong>The</strong> modeled<br />

weights were <strong>the</strong>n calculated from <strong>the</strong> modeled counts in such a way that <strong>the</strong> weights in a given<br />

quarter summed to one. For example, Figure A4 shows <strong>the</strong> modeled and observed weights for<br />

Chicago.<br />

Modeling <strong>the</strong> weights achieved two objectives. Firstly, it smoo<strong>the</strong>d over <strong>the</strong> random fluctuations<br />

in quarters where data existed, and secondly, it provided estimates (extrapolations and<br />

interpolations) in quarters where data was unavailable. Overall <strong>the</strong> modeled weights appeared<br />

A-16

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