As!a!result,!to!properly!assess!the!effect!that!a!driver’s!ra ce/ethni city!has! o n!the! l ikelih ood !that!
he!or!she!will!be!stopped,!researchers!must!develop!a!benchmark!that!enables!the!co mparison !
of!actual!stop!rates!with!a!driver’s!risk!of!being!stopped!in!the!absence!of!bias.
41
!An!appropriate!
benchmark! must! incorporate! the! various! legal! and! non-legal! factors! that! shape! stop! risk,!
including!when,!where,!and!how!often!they!drive,!the!make,!model,!and!condition!of!their!car,!
and!their!behavior!and!demeanor!while!driving.
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!
!
The! most! common! approach! to! thi s! challenge! has! been! to! draw! on! U.S.! Census! fi gures! to!
capture!a!j urisd ictio n’s!demographic!profile!and!then!use!these!data!to!make!inferences!about!
the!city’s!driving!population.
43
!Though!inexpensive!and!relatively!easy!to!i mpl ement,!the!u se!of!
Census! data! has! come! under! heavy! criticism! for! its! inability! to! accurately! reflect! not! only! a!
jurisdiction’s! driving! population,! but! the! various! other! risk! factors! at! play.
44
! Other! statistical!
proxies,!including!drivers’!license!data
45
!and!no-fault!traffic!accident!figures,
46
!have!also!been!
used!to!address!these!limitations.!!
!
Other! researchers! have! made!efforts! to!observe! the! characteristics! of! the! driving! population!
first!hand.!Rather!than!relying!on!outside!information!as!the!benchmark,!some!have!attempted!
to! chart! the! demographic! profile! of! a! jurisdiction’s! drivers! at! various! locations! an d! times! of!
day.
47
!The!observational!approach!is!both!expensive!and!time-consuming,!and!not!without!its!
own!challenges.
48
!
!
41
!Tillyer,!R.,!Engel,!R.S.,!&!Cherkauskas,!J.C.!(2010).!Best!practices!in!vehicle!stop!data!collection!and!analysis.!
Policing:$An$International$Journal$o f$P olic e $Str at eg ies $& $Management,!33(1),!69-92.!
42
!Fridell,!L.A.!(2004).!By$the$numbers:$A$guide$for$analyzing$race$data$from$Vehicle$Stops.!Washington,!D.C.:!Po lice !
Executive!Research!Forum;!Ridgeway,!G.!&!MacDonald,!J.!(2010).!Methods!fo r!assessing!racially!biased!policing.!In!
S.K.!Rice!&!M.D.!White!(Ed s.)!Race,$ethnicity,$and$policing:$New$and$essential$readings!(pp.!180-204).!New!York:!
New!York!University!Press;!Tillyer,!R.,!Engel,!R.S.,!&!Cherkauskas,!J.C.!(2010).!Best!practices!in!vehicle!stop!data!
collection!and!analysis.!Policing:$An$International$Journal$of$Police$Strategies$&$Management,!33(1),!69-92;!and!
Walker,!S.!(2001).!Searching!for!the!denominator:!Problems!with!police!traffic!stop!data!and!an!early!warning!
system!solution.!Justice$Rese a rc h$a n d $Po lic y,!3,!63-95.!
43
!Cordner,!G.,!W illiams,!B.,!&!Zuniga,!M.!(2001).!San$Diego$Police$Department$vehicle$stop$study:$Yea r$end$report.!
San!Diego,!CA,!p.!ii;!Cordner,!G.,!Williams,!B.,!&!Velasco,!A.!(2002).!San$Diego$Police$Department$vehicle$stops$in$
San$Diego:$2001.!San!Diego,!CA .!
44
!Engel,!R.S.,!Frank,!J.,!Klahm ,!C.F.,!&!Tillyer,!R.!(2006,!Jul.).!Cleveland$Division$of$Police$Traffic$Stop$Data$Study:$
Final$Report.!Cincinnati,!OH:!Univ e rsity !of !Cin cin n ati!D iv isio n !of!C riminal!Justice.!!
45
!Fridell,!L.A.!(2004).!By$the$numbers:$A$guide$for$analyzing$race$data$from$Vehicle$Stops.!Washington,!D.C.:!Po lice !
Executive!Research!Forum.!
46
!Alpert,!G.P.,!Dunham,!R.G.,!&!Smith,!M.R.!(2007).!Investigating!racial!profiling!by!the!Miami-Dade!police!
department:!A!multimethod!approach.!Criminology$&$Public$Policy,!6,!25-56.!
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!E.g.,!Lamberth,!J.C.!(2013,!Sept.).!Final$Report$for$the$City$of$Kalamazoo$Department$of$Public$Safety.!West!
Chester,!PA:!Lamberth!Consulting.!
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!Engel,!R.S.,!&!Calnon,!J.M.!(2004).!Comparing!benchmark!methodologies!for!po lice-citizen!contacts:!Traffic!stop!
data!collection!for!the!Pennsylvania!State!Police.!Police$Quarterly,!7,!97-125.!