Assessing the Effect of Race Bias in Post-traffic Stop Outcomes Using Propensity Scores

“…examples represent a mere fraction of a decades-long, multidisciplinary effort to quantify the degree to which police discriminate against civilians of color [see Atiba Goff and Kahn (2012), Fridell (2017), and Ridgeway and MacDonald (2010) for more extensive reviews of this empirical literature].”

“The reference work for the propensity score approach can be found in Ridgeway (2006), who adopts risk difference as a discrimination measure, called the race effect, and estimates propensity scores by logistic regression on a data set of the Oakland Police Department.”

“In a novel design, Grogger and Ridgeway (2006) analyzed traffic stops in Oakland and showed that the racial distribution of stopped individuals during the day, when a suspect’s race is readily apparent, matches the distribution at night, when the “veil of darkness” masks race, and thus concluded…”

“McCaffrey et al. (2004) applied the method to the study of the effect of a community-based, residential drug treatment program on alcohol and marijuana use among juvenile probationers (see Ridgeway 2006, for an application of GBR to racial bias in citation rates, search rates, and stop duration in police traffic stops…”

“Other studies have noted racial disparities in poststop outcomes, such as stop duration and search rates (Ridgeway 2006).”

“Ridgeway (2006) and McCaffrey et al. (2004) discussed a method that can be applied to studies that utilize propensity score weights and is available in the “twang” package for R. Methods are also available that yield nonparametric bounds on the treatment effects, without characterizing the…”

“…traffic stops reveals that Blacks and Hispanics are more likely than Whites to be stopped and searched by the police (e.g., Alpert, MacDonald, and Dunham, 2005; Borooah, 2011; Close and Mason, 2007; Durose, Schmitt, and Langan, 2005; Engel and Calnon, 2004; Engel and Johnson, 2006; Ridgeway, 2006).”

“For example, Ridgeway (2006) found that black drivers were twice as likely as white drivers to be searched after being stopped, and only 18% of the searches led to an arrest.”

“In the context of policing, for example, a clear racial disparity exists in that officers are more likely to stop Blacks and Latinos compared to Whites (Ridgeway, 2006).”

“The effective sample size is a measure of the number of “other cases” that are reasonably comparable with the BD–WV cases (Ridgeway, 2006: 15).”

“…stereotyped as criminals (Eberhardt, Goff, Purdie, & Davies, 2004; Niemann, Jennings, Rozelle, Baxter, & Sullivan, 1994), to be stopped by police (Ridgeway, 2006), are more likely to be searched (Gelman, Fagan, & Kiss, 2007), are exposed to more force in interactions (Walker, Spohn, & DeLone,…”

“For more detailed analysis of propensity score weights see Hirano and Imbens (2001), Wooldridge (2001, pp. 614–621), McCaffrey, Ridgeway, and Morral (2004), and Ridgeway (2006).”

“Propensity score weighting deals better with confounding variables that are correlated with both race and the outcome of interest (perceptions of injustice by the police) (Rosenbaum, 1987; Hirano and Imbens, 2001; Wooldridge, 2002; Imbens, 2004; McCaffrey et al., 2004, Ridgeway, 2006).”

“We also used propensity score weighting [24–26].”

“Using data from the U.S. Sentencing Commission for fiscal years 2006–2008, Franklin utilized propensity score weighting (Ridgeway, 2006) and approximate propensity score matching to develop an appropriate sample for observation.”

“For example, Barsky, Bound, Charles, and Lupton (2002) and Ridgeway (2006) used propensity score adjustment to help explain the wealth gap between blacks and whites and to measure the extent of racial profiling in traffic stops, respectively.”

“Brennan, & Earls, 2005; El-Bassel, Gilbert, Wu, Go, & Hill, 2005; Gangl, 2006; Hahs-Vaughn & Onwuegbuzie, 2006; Hill, Waldfogel, Brooks-Gunn, & Han, 2005), including criminology to estimate treatment effects on outcomes (King, Massoglia, & MacMillian, 2007; Ridgeway, 2006; Sampson, Laub, & Wimer, 2006; Tita & Ridgeway…”

“Analyses of discretionary searches in Oakland using propensity score matching indicated that Black drivers were twice as likely to be searched for probable cause reasons compared with White drivers (Ridgeway, 2006); interestingly, no effect was discovered when consent searches were examined.”

“ing about racial disparity from a causal standpoint (Paternoster & Brame, 2008; Ridgeway, 2006).”

“A related strategy has appeared in past research for assessing sensitivity to hidden bias in the context of a propensity score weighting-based evaluation of a binary treatment (Ridgeway, 2006).”

“…jurisdictional studies of traffic stop and search disparities is their lack of control for variation in social demographics and police deployment across neighborhoods or beats (Fagan, Geller, Davis, & West, 2010; Gaines, 2006; Ridgeway, 2006; Schell, Ridgeway, Dixon, Turner, & Riley, 2007).”

“In our experience weights estimated using a generalized boosted model (GBM) following the methods of McCaffrey, Ridgeway and Morral (2004) as implemented in the Toolkit for Weighting and Analysis of Nonequivalent Groups, the twang package for R, tend not to show the extreme behavior that resulted from logistic regress…”

“several advantages over traditional regression-based analyses (48,50).”

“Racial profiling within automobile stops has focused on three distinct officer-initiated decision-making points that can measure the presence of racial and/or ethnic nonneutrality (Schafer, Carter, Katz-Bannister, & Wells, 2006; see also Barnum & Perfetti, 2010; Ridgeway, 2006; Tillyer, Engel, & Cherkauskas, 2010).”

“Ridgeway (2006) has argued for the use of propensity scores as an alternative to current regression techniques, which are used to parcel out the specific influences from various factors potentially associated with poststop outcomes.”

“However, this method was criticized as being highly sensitive to the form of the model and the inclusion of important interaction terms (Imbens 2004; Ridgeway 2006).16 Therefore, this study uses the methodology of doubly regression estimation to identify the effect of the guilty plea on case…”

“These approaches have the advantage over traditional regression in that they assure that the bivariate distributions of covariates are equivalent (Ridgeway, 2006).”

“For example, if officers are more likely to misclassify Hispanic motorists as White when it is dark, then results from Veil of Darkness tests may also underestimate the relative risk that Hispanic motorists will encounter the police (Grogger & Ridgeway, 2006).”

“PSM has been used to examine a variety of issues in criminological research (e.g., Gibson, Miller, Jennings, Swatt, & Gover, 2009; King, Massoglia, & Macmillan, 2007; Ozer & Engel, 2012; Ridgeway, 2006).”

“Here, we used methods described by Ridgeway (2006) and implemented in the R package twang.”

“However, as Ridgeway (2006) has noted, there is reason to question the use of regression analyses when the treatment and control groups differ “substantially” on some set of independent variables, x.”

“For an in-depth discussion of this type of sensitivity analysis, we direct the interested reader to Ridgeway (2006).”

“| 235HONG et al. Ridgeway and colleagues (McCaffrey et al, 2004; Ridgeway, 2006) proposed a different SA strategy for weighting-based ATT analysis.”

“Fourth waiver searches involve an ambiguous level of officer discretion (Hetey, Monin, Maitreyi, & Eberhardt, 2016; Ridgeway, 2006).”

“by the police (Peffley & Hurwitz, 2010), and police are more likely to punish Black suspects (Close & Mason, 2006, 2007; Ridgeway, 2006).”

“Despite concern about the use of PSM for creating comparison groups based on a condition where the subject has no chance to be in either condition, such as gender or race (Shadish, 2013), PSM has been used frequently as a means to delineate groups based on race (Higgins, Jennings, Jordan, & Gabbidon, 2011; Higgins, Ri…”

“, 2004, 2013) and the effect of driver race on traffic stop outcomes (Ridgeway, 2006).”

“uation of criminal justice/drug policy (McCaffrey, Ridgeway, & Morral, 2004; Ridgeway, 2006; Tita et al., 2003) as well as measuring the costs of crime (Greenbaum & Tita, 2004).”

“Consistent with racial profiling literature using both official data (Meehan & Ponder, 2002; Ridgeway, 2006) and citizens’ personal accounts (Stewart et al., 2009), Blacks and Hispanics who were stopped in cities other than the ones of their home residence were more likely to believe these stops to…”

“This score was calculated using generalized bootstrap modeling in the R Twang package (Ridgeway, 2006) based on 42 confounding variables, including several maternal characteristics such as age, education, race, diet, health and pregnancy history, alcohol, marijuana and prescription medicine…”

“Estimation of propensity scores using GBR is implemented using the twang package for R (Ridgeway et al. 2006); further details on estimation of propensity scores using GBR and the twang package can be found in Ridgeway (2006).”

“In the literature, police discretion is generally regarded as a factor which facilitates and increases racial and ethnic discrimination (Mastrofski 2004, Talley et al. 2005, Ridgeway 2006, Bowling and Phillips 2007, Walsh and Taylor 2007, Gau and Brunson 2010, Van der Leun and Van der Woude 2011).”

“Recent additional approaches include (Anbarci & Lee, 2008; Blalock et al., 2007; Pickerill et al., 2009; Ridgeway, 2006).”

“Thus, the PSM methodology can help to better account for potential confounding influences on the relationship between foreclosure and crime and to more directly estimate foreclosure’s impact (e.g., Apel & Sweeten, 2010; Ridgeway, 2006; Rosenbaum, 1987; Wooldredge, 2007).”

“Stop-and - frisk policing, for instance, is commonly blamed for inflated arrests counts attached to individuals from disadvantaged neighborhoods even when the scientific evidence can be equivocal (Grogger & Ridgeway, 2006, Ridgeway, 2006).”

“The effect of status on behavior depends on the degree of legitimacy granted to unequal distribution of power (Ridgeway 2006).”

“1 (Friedman, 2002; McCaffrey et al., 2004; R Development Core Team, 2008; Ridgeway, 2006).”

“This paper is not intended to present a definitive solution to the problems arising from the use of PS, given the validity of other methods available for estimating PS (Ridgeway 2006) as well as several other methods for matching and balancing treatment and Control groups (Stuart 2010).”

“Researchers then used other methods to develop these benchmarks, including propensity score matching (Ridgeway, 2006; Ridgeway & MacDonald, 2009) and outcomes testing (Engel, 2008; Engel & Tillyer, 2008; Knowles, Persico, & Todd, 2001).”

“PSM, which has been growing in popularity in criminological research (see Jennings et al., 2014; Loughran et al., 2015; Peck & Jennings, 2016; Ridgeway, 2006), simulates a quasi-experimental design as it estimates the impact of a treatment on an outcome for cases that have had identified systematic…”

“The approach used in this study to estimate PS probabilities was based on Ridgeway (2006), who presented an application of PS estimation using the general boosting method; Table 2 Variables used for propensity scoring Knowledge area that method is frequently employed to analyze classification and…”

“Ridgeway (2006) provides an empirical example of ATT in his analysis of the role of racial biases in traffic stop outcomes, by using propensity score weighting (McCaffrey et al. 2004).”

“[33] Ridgeway, Greg.”