Informing America's Policy on Illegal Drugs What We Don't Know Keeps Hurting Us (2001) / Chapter Skim
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Appendix A: Characteristics of STRIDE Cocaine Data
Appendix A: Characteristics of STRIDE Cocaine Data
Pages 281-295
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Appendixes
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with substantial numbers of black and Hispanic students were sampled at higher rates than other schools. The final stage of sampling consisted of randomly selecting one or two intact classes of a required subject, such as English or social studies, from grades 912 at each chosen school.
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The committee is confident, however, that the main qualitative conclusions reached using its version of STRIDE would also be reached using other versions. SPARSENESS OF THE DATA There are over 160 DEA field offices in the United States.
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Thus, the STRIDE data can be used to construct a national price index for cocaine only by assuming that price functions in different cities are similar in certain ways but the STRIDE data can be used to show that the required assumptions are false. VARIABILITY OF SAMPLE CHARACTERISTICS The characteristics of the STRIDE data vary greatly among the cities in which the number of observations is relatively large.
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Boston is also smaller than New York, but in 19961998 there were more purchases in Boston than in New York. Figure A.2 shows year-to-year variations in the fraction of cocaine purchases of amounts of 5 gm or less in each of four cities.
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For example, the ratio of the highest to lowest median purchase is 13 in Boston and 20 in New York. In 1996, the median quantity purchased in Detroit was 20 times larger than the median quantity purchased in Boston.
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of Purchases of Cocaine Base in Four Year Boston Detroit New York Washington 1994 26 22 15 14 1995 14 48 7 7 1996 2 41 6 9 1997 3 23 3 26 1998 6 18 60 21 there. In addition, the relatively low proportions of purchases of below 5 gm shown in Figure A.2 and the larger-than-retail-size median purchase sizes shown in Table A.1 reflect the DEA's focus on large cocaine dealing operations.
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In summary, the STRIDE data display characteristics that are consistent with the conclusion that the DEA's data acquisition criteria vary greatly among cities and over time within cities. The characteristics are also consistent with the conclusion that the STRIDE data are not representative of cocaine markets in the cities in which purchases are made.
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The figure shows predicted median prices of 0.8 gm of 65 percent-pure powder cocaine and cocaine base that is purchased in the central city. The predicted values are obtained from the formula A A A A A (A.2)
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. In other words, the test rejects the hypothesis that the price functions of powder cocaine and cocaine base are equal.
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Consequently, a price index that is obtained by combining price data from different cities can produce misleading results (see the example in Chapter 3~. This section uses STRIDE data for cocaine base to illustrate the differences among the price functions of different cities.
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Moreover, intercept shifts cannot account for differences among cities or over time in the slope coefficients ,B1 - ,B3. The committee is 4The test procedure described in footnote 3 rejects the hypothesis that the price functions are the same in all cities (p < 0.01~.
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Thus, although combining data from different cities is unavoidable to obtain national-level price indices from STRIDE, such indices are likely to be misleading. PRICES IN THE STRIDE DATA MAY NOT BE REPRESENTATIVE OF MARKET PRICES The results presented in the previous sections show that the STRIDE data are sparse, that they reflect variations in law enforcement strategies among cities and over time, that different forms of cocaine have different prices, and that prices are different in different cities.
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The figure shows the estimated median prices of 0.8 gm of 65 percent pure cocaine base that are obtained using the DEA and MPDC data. The two sets of estimates are very different.
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It is also possible that neither dataset accurately represents true market conditions. Without evidence on this matter, the STRIDE data cannot be relied on to provide accurate estimates of cocaine prices and price changes.
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