1. Gary Klass Department of Politics and Government Illinois State University

2. Reliability and Validity Reliability: consistency in measurement Assuming you don’t get any smarter, how much will your ACT score change every time you take the test? Validity: Does it measure what it is supposed to measure? What do ACT scores measure?

3. Reliability Consistent Measurement Across time, across cities, countries (note births to unwed mothers in the US T 1291)note births to unwed mothers in the US Testing effects (scores improve the second time). Instrumentation (changing procedures for recording the data). Sampling error.

4. Comparisons of Two Indicators

5. “Crime halved under Mr. Giuliani and murders fell by two-thirds, transforming New York from one of the most dangerous cities in America to one of the safest.” “From America's mayor to America's President?,” The Economist.com (3 May, 2007) D OES G IULIANI DESERVE CREDIT FOR NYC’ S FALLING CRIME RATE ?

6. N EW Y ORK C ITY C RIMES, 1993-2001 (Thousands)

7. C OUNTER A RGUMENTS : William Bratton, not Giuliani, deserves credit* Regression artifact – end of crack epidemic Decline started under Dinkins* Crime went down in other cities too (Freakonomics) Most of the reduction was for minor crimes* Bad data: CompStat led to underreporting* The economy improved* Dinkins hired more officers (Freakonomics) * Wayne Barrett.

8. D INKINS ? V IOLENT C RIME R ATES, N EW Y ORK C ITY, 1985-2007 (per 100,000 population)

9. O THER C ITIES ? R OBBERY R ATES, T EN L ARGEST C ITIES, 1985-2007 *BJS: Data Online

10. O THER C ITIES ? FBI\UCR V IOLENT C RIME R ATES : 69 L ARGEST C ITIES, 2007 (population > 250,000)

11. J UST MINOR CRIMES ? V IOLENT AND P ROPERTY I NDEX C RIMES (thousands) -52%

12. B AD D ATA ? FBI AND NCVS V IOLENT C RIME R ATES, 2007 (population > 250,000)

13. B AD D ATA ? M URDER R ATES : N EW Y ORK C ITY AND 69 L ARGEST C ITIES, 2007 ( POPULATION > 250,000)

14. B AD D ATA ? M URDER R ATES : N EW Y ORK AND 69 L ARGEST C ITIES, 2007 (population > 250,000)

15. T HE E CONOMY ?

16. P OLICE H IRING ? S WORN O FFICERS, N EW Y ORK C ITY P OLICE D EPARTMENT, AND V IOLENT C RIME R ATE 1992-04 General Accounting Office. “COMMUNITY POLICING GRANTS COPS Grants Were a Modest Contributor to Declines in Crime in the 1990s” http://www.gao.gov/new.items/d06104.pdf

17. P OLICE H IRING ? C HANGE IN C RIME R ATES AND S WORN P OLICE P ERSONNEL, IN THE 1990 S, 58 L ARGEST C ITIES