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VSP Racial Dispari.es Analysis, 2010-‐15
Stephanie Seguino and Nancy Brooks May 30, 2016
Focus of analysis
• The analysis concentrates on traffic stops and outcomes that are the result of officer discre.on.
• We therefore ignore: – externally generated stops – arrests with warrant
• We calculate search rates in 2 ways: – Probable cause and reasonable suspicion only – All searches (incl. searches on warrant).
Mul.ple outcomes
• We have made sure to count only one stop per driver (even if there are mul.ple outcomes per stop).
Five indicators
1. Stop rates compared to share of the popula.on 2. Share of stops that lead to: • Warning vs. 1cket (cita1on) • Arrest • Search
3. Percentage of searches with contraband 4. Trooper dispari1es in stop rates 5. Racial dispari.es by barracks
Table 1. Stops and Stop Rates by Race/Ethnicity, 2010-‐15
Year White Black Asian Hispanic
Total number of stops 259,903 5,554 3,562 2,568
Share of stops 95.6% 2.0% 1.3% 0.9%
Share of population 95.1% 1.6% 1.8% NA
• Popula.on is from US Census for 2010-‐14. • We do not use accident data to es.mate the driving popula.on because 22%
of VSP reported accidents are missing race of driver.
Figure 1A. Trends in black stop rates and share of popula.on, 2010-‐2015
1.8% 1.8% 1.9% 1.9%
2.3% 2.4%
1.6% 1.6% 1.6% 1.6% 1.6% 1.6%
1.2%
1.4%
1.6%
1.8%
2.0%
2.2%
2.4%
2.6%
2010 2011 2012 2013 2014 2015
Black share of stops Black share of population
Figure 1B. Trends in Asian share of stops and popula.on
1.1% 1.1% 1.2%
1.3%
1.5% 1.5%
1.3%
1.8% 1.8% 1.8% 1.8% 1.8% 1.8% 1.8%
0.8%
1.0%
1.2%
1.4%
1.6%
1.8%
2.0%
2010 2011 2012 2013 2014 2015
Asian share of stops Asian share of population
Table 1. Summary of Outcome Rates
by Race, 2010-‐15
*Excludes externally generated stops.
Table 4. Data quality Number of Incident Reports with Missing/
Unknown Data, 2010-‐15
Figure 2. Trends in black and white .cket rates, 2011-‐15
43.7%
38.9% 37.7%
32.3% 35.6%
37.4%
53.6%
45.0%
40.8% 38.3%
41.2% 42.2%
20%
25%
30%
35%
40%
45%
50%
55%
60%
2011 2012 2013 2014 2015
White Black
Figure 3. Trends in black and white arrest rates, 2011-‐15
1.08% 1.02% 1.05% 1.00% 0.94%
2.22% 2.11% 2.07%
1.54%
2.02%
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
2011 2012 2013 2014 2015
White Black
Figure 4. Trends in Black and White Search Rates,
2011-‐15
0.9% 0.9% 1.1% 1.2% 0.9%
3.6% 3.6%
4.9%
6.0%
5.1%
0.0%
1.0%
2.0%
3.0%
4.0%
5.0%
6.0%
7.0%
2011 2012 2013 2014 2015
White Black
Figure 5. Trends in percentages of consent searches yielding contraband, 2011-‐15
(excludes warnings)
58.0% 55.3%
60.9%
71.6% 74.7%
40.0%
26.5%
40.4%
59.5% 60.4%
20%
30%
40%
50%
60%
70%
80%
2011 2012 2013 2014 2015 White Black
Figure 6. Blacks as % of stops by trooper, 2010-‐2015, (excludes externally generated stops), 100+ stops
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
1 10
19
28
37
46
55
64
73
82
91
100
109
118
127
136
145
154
163
172
181
190
199
208
217
226
235
244
253
262
271
280
289
Officers ranked by black drivers as % of all stops
Blacks as share of stops
Blacks as share of popula.on
Figure 7. Hispanics as % of trooper stops, 2010-‐2015, (excludes externally generated stops), 100+ stops
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
4.0%
4.5%
5.0%
1 10
19
28
37
46
55
64
73
82
91
100
109
118
127
136
145
154
163
172
181
190
199
208
217
226
235
244
253
262
271
280
289
Officers ranked by Hispanic drivers as % of all stops
Hispanics as share of stops
Figure 14. Percentage of stops with race as unknown or missing, by trooper
0%#
2%#
4%#
6%#
8%#
10%#
12%#
152#
286#
428#
431# 65# 7# 47#
277#
155#
404#
150#
419#
105#
326# 25#
148# 53#
115# 99#
340#
180#
165#
227#
398#
178#
422#
386#
313#
297#
405# 50#
337#
338#
254#
379#
423#
182#
Unknowns'as'%'total'stops'
Figure 9. Ticket rates by barracks, 2010-‐15
46.0%
40.6%
36.6%
52.4%
45.2%
38.3%
30.4%
26.4%
36.4%
28.2%
32.9% 34.0% 35.0%
20%
25%
30%
35%
40%
45%
50%
55%
Figure 10. White and black search rates by agency, 2010-‐15
1.4% 1.0% 0.8% 1.4% 1.2%
0.7% 0.7% 1.3% 1.6%
8.4% 8.2%
1.6%
4.2%
6.8%
2.8% 4.0%
7.3%
3.2%
0% 1% 2% 3% 4% 5% 6% 7% 8% 9%
White Black
• Only barracks with 10+ searches of black drivers shown here.
Figure 11. Hit rates on consent searches by barracks, 2010-‐15
67.1%
57.4%
64.3% 68.0%
54.5%
63.4% 66.2%
69.1%
58.9%
42.0%
32.7%
81.8%
50.0% 46.2%
35.0%
60.0% 65.4%
47.1%
20%
30%
40%
50%
60%
70%
80%
90%
White Black
Figure 12. Ra.o of black/white search rates
6.0
8.4
2.0 3.0
5.6
3.8
6.0 5.5
2.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Table 4. Sta.s.cally Significant Racial Dispari.es in Outcomes
Differences between Seguino/Brooks and McDevic Studies
Where our methods are the same, the two studies produce similar results. However, our methods differ in several ways. 1. Our study evaluates trends over .me. 2. We disaggregate by race for all indicators, thereby highligh.ng
dispari.es among minori.es. We do not report on Na.ve Americans due to small sample size.
3. We exclude externally generated stops. 4. We calculate hit rates in cases where a .cket or arrest occurs
(excluding warnings). 5. We use U.S. census bureau data for driving popula.on es.mates
due to poor quality of accident data. 6. We provide the raw data on which our analysis is based.
Con.nued • Where McDevic uses Census data, his are for 2010, while
ours are for 2010-‐14. • Our results on .cket rates are very similar, and differences
likely due to our exclusion of externally generated stops (EGS).
• Our search rate of blacks is lower likely again due to our exclusion of EGS.
• There are differences in hit rates in the two studies (both overall and by barracks), likely due to our exclusion of EGS, as well as our calcula.on of hit rate that includes and excludes warnings. The lacer, we argue, is the more salient. Our study shows wider gaps in hit rates, sugges.ve of inefficient policing and bias.