Sparrow—One Week in Heron City (Case B) | 1
New Perspectives in Policing
IntroductionThe Heron City case study is divided into three parts — Case A, Case B and Teaching Notes. The case study is
designed to serve as a basis for discussions regarding: (a) the relationships among a range of current policing
strategies, and (b) the nature of analytic support that modern operational policing requires.
The broad strategic or organizational approaches discussed in the case study include:
• Communitypolicing.
• Compstat(asanorganizationalapproachtocrime-reductiontasks).
• Problem-orientedpolicing.
• Evidence-basedpolicing.
• Intelligence-ledpolicing.
One Week in Heron City (Case B)A Case Study
Malcolm K. Sparrow, Ph.D.
S e P t e m B e r 2 0 0 9
National Institute of Justice
Executive Session on Policing and Public Safety This is one in a series of papers that will be published as a result of the Executive Session on Policing and Public Safety.
Harvard’s Executive Sessions are a convening of individuals of independent standing who take joint responsibility for rethinking and improving society’s responses to an issue. Members are selected based on their experiences, their reputation for thoughtfulness and their potential for helping to disseminate the work of the Session.
In the early 1980s, an Executive Session on Policing helped resolve many law enforcement issues of the day. It produced a number of papers and concepts that revolutionized policing. Thirty years later, law enforcement has changed and NIJ and Harvard’s Kennedy School of Government are again collaborating to help resolve law enforce-ment issues of the day.
Learn more about the Executive Session on Policing and Public Safety at:
NIJ’s Web site: http://www.ojp.usdoj.gov/nij/topics/law-enforcement/executive-sessions/welcome.htm
Harvard’s Web site: http://www.hks.harvard.edu/criminaljustice/executive_sessions/policing.htm
Sparrow—One Week in Heron City (Case B) | 3
One Week in Heron City: Case B
Heron City is fictional. So are all the characters in the following narrative.
Wednesday, Late Morning: Nigel Jewett, Junior Analyst, IT1 ServicesAsChiefHarrisonwasleavingtheITdepartmentafterhermeetingwithITDirectorPhilGoring,shestoppedto
say hello to Nigel. Nigel showed her some license plate images on his computer screen, which the Chief agreed
were pretty easy for the human brain to interpret, and which the system ought to have read correctly. Nigel
explained to the Chief that the biggest problem was the system’s failure to distinguish between six and eight,
particularly if a license plate was dirty. He believed that the misreading of sixes and eights, where the software
interpreted one of these digits as the other, accounted for about 80 percent of the errors he had examined. The
nextbiggestsourceoferrorswasfailuretodistinguishtheletter“I”fromthenumber“1.”
AsChiefHarrisonwasabouttoleave,Nigelaskedher,somewhatshyly,ifhecouldtalktohersometime.“About
anythinginparticular?”sheasked.“Aboutstolencars,”hereplied.Shetoldhimshewasabouttogoandfinda
cupofcoffeeinthecafeteriaandaskedhimifhe’dliketowalkdownwithher.
FollowingareexcerptsfromthefirstmeetingbetweenChiefLauraHarrisonandNigelJewett,junioranalyst,IT
department.Themeetingtakesplaceintheheadquarterscafeteria.
Chief Harrison: IunderstandfromMr.Goringthatyourjobisprettyrepetitive.Weappreciateyoudoing
thisanalysis.Iunderstanditisimportantforthesakeofimprovingthesystem.SoIhope
you can stand it.
Nigel Jewett: Isupposeitisimportant.ButitiscertainlynotwhatIliketodo.
Chief Harrison: Whatdoyouliketodo?
Nigel Jewett: Dataanalysis.Imajoredinoceanographyandmarinebiology,andIjustlovetofindout
thewaytheworldisandthewayitworks.
Chief Harrison: Whatyou’redoingisn’tdataanalysis?
1 Information Technology
4 | New Perspectives in Policing
Nigel Jewett: No.Nobodyheredoesmuchdataanalysis.WhatI’mdoingisdataqualityanalysis.As
iftheendgoalistohaveavastlibraryofperfectdata!What’sthepointofhavingavast
libraryofperfectbooksifnobody’sreadingthem?
Chief Harrison: Whatsortofanalysisdoyouliketodo?
Nigel Jewett: Oh,allsorts.Whateverhelpsfindouthowthingswork.WhenIwaseightyearsold,my
parentsgavemeabookcalledHow Things Work,andeversincethenI’vebeentaking
thingsapartandsometimes[hesmiles]puttingthembacktogetheragain.Then,incollege
Idiscoveredhowtotaketheworldapartusingarangeofdatasources,andI’mwaiting
forajobatNOAA,2whichthey’vepromisedme,soIcanstartdoingthatkindofworkall
over again.
Chief Harrison: Whatisityouwanttotakeapart,onceNOAAletsyouin?
Nigel Jewett: Idoneedtotellyousomethingaboutthestolencars.ButwhatIreallywanttoworkon,
at NOAA, is hypoxia.
Chief Harrison: Hypoxia?Forgivemyignorance.Whatishypoxia?
Nigel Jewett: Deadzonesintheocean.ParticularlyintheGulfofMexico.Theyareseasonal,butthey’re
getting bigger. They can be hundreds of miles across now. One year, the hypoxic zone in
theGulfwasasbigasthestateofMassachusetts.
Chief Harrison: Deadzones?
Nigel Jewett: Yes. No oxygen, or extremely low levels of oxygen, from the bottom of the ocean all the
way up to a depth of about 9 meters. Hypoxia is related to excessive nutrient loadings and
red tides, but it is a distinct phenomenon and not the same as red tide and algae blooms,
whicharemuchbetterknownandbetterunderstoodonthewhole.
Chief Harrison: So,howdoyoustudysuchathing?Howdoesthatrelatetodataanalysis?
2 The National Oceanographic and Atmospheric Administration
Sparrow—One Week in Heron City (Case B) | 5
Nigel Jewett: OneofmyspecialtieswasSONAR.3IusedtolovesiftingthroughdatabasesofSONAR
andsoundrecordingsandfiguringouthowwemightormightnotbeabletomonitor
thesedeadzones.Ortheiredges.Shoalsoffishgatheraroundtheedgesofthezone.They
can’t go into it because they can’t breathe.
Chief Harrison: Isthattypicalofthetypeofworkthatmarinebiologistsdo?
Nigel Jewett: Well,Iliketodoanythingthatinvolvesfindingmeaning,orpatternsorstructures,from
hugedumpsofotherwiseuselessdata.That’swhatImeanbydataanalysis.
Chief Harrison: Whatsortofpatternsdoyousearchforinmarinebiology?
Nigel Jewett: Allkindsofthings.There’soneclassofanalysiswhereyoulookforthingsyoucandescribe
butthatshouldn’thappen.Likeahypoxicareabecausetherearenocrabsonthebottom
whenthereshouldbe,andnoshoalsoffishformiles.Whereabottom-trawlwouldcome
up with no living organism. And for very different types of research, other oddities, for
example:afemaledolphintravelingalone.Dolphinsdon’tgenerallytravelalone,except
for the older males who peel off when it’s time to go off and die. First you describe what
you’relookingfor.Thenyouworkoutwhatthedatarepresentationofthatthingwould
looklike,ifitexisted,withinthedatathatyouhaveordatayoucanget.Thenyouwork
outhowtosearchforitwithinthedatawithoutevenknowingwhetheritmightbethere
or not.
Chief Harrison: Are there other classes of analysis you use?
Nigel Jewett: Yes.Anotherbigcategoryisdeviationsfromknownpatterns.Whenmigrationpatterns
change.Whenoceantemperaturesdeviatefromseasonalnorms.That’sparticularly
important for many species in spawning seasons. A couple of degrees off normal is
enoughtosubstantiallyreduceaspawningyield.AndIdidsomeworkonceonearly
signsofsicknessandstressincoralreefecosystems.
Chief Harrison: Canyoutellifpeoplearesick?Ifthepopulationhadfluforinstance?Fromdataanalysis
of various types?
3 Sound navigation and ranging (SONAR) is a method of locating objects in the water and determining their echo characteristics.
6 | New Perspectives in Policing
Nigel Jewett: I’msureyoucan.Googlecan.Theycanseehowmanypeoplearelookingup“flusymptoms”
forinstance.Youcouldwatchsalesofhealth-relateditemsorprescriptions,assuming
youcancollectallthatdatafromthepharmacies.Epidemiologistshaveallthosekinds
ofmonitoringsystems,I’mprettysure.
Chief Harrison: Couldyoutellafluoutbreakfromtrafficpatterns?Iguessyoucouldseeiftherewasany
dipinoveralltrafficvolume,andthatmightgiveyouacitywideindication.
Nigel Jewett: Youcouldprobablydomuchbetterthanthat.Maybeifyoufocusedoncommuters.
Chief Harrison: Couldyoupickoutthecommuters?
Nigel Jewett: Sure.Atleast,youcouldifyoucouldjustgetthedataontosomeusableplatformwhereyou
couldplaywithit.Wedon’thavesuchathinghereatthemoment.Butyoucouldidentify
thecommutersbythefactthattheywouldexhibitadaily-repeatpatternintheirmove-
ments.Andthenifyouwereinterested,youcouldcountby10a.m.—forinstance—how
manyofthenormalThursdaymorningcommutershadnotgonetoworkthisparticular
Thursday. That might be more accurate than overall volume, because you could ignore
allthetrafficpassingthroughandthetourists,andallofthatothernoise.
Chief Harrison: Couldyoutellifsomeonewasbeingfollowed,fromtheALPRdata?
Nigel Jewett: Someoneinparticularorsomeoneingeneral?
Chief Harrison: Someoneinparticular.LikeHayleyScott.
Nigel Jewett: Shouldbeableto.It’saneasyenoughpatterntodescribeandthensearchfor.Onecar
following close behind another, and doing it more often than you’d expect by chance.
Chief Harrison: AreyouawarethattheScottmurderinquiryhadanoutsidecontractorlookatthisalready?
Andtheydidn’tfindanythingofinterestexceptthatherhusbandoftenescortedherhome,
which is hardly surprising in the circumstances.
Nigel Jewett: Ididn’tknowthat’swhatthedumpwasfor.Mybossaskedmetodothedatadumpofone
month’sALPRdata,whichIdid,wartsandall.Heonlytoldmehehadaspecialprojectto
doforthedetectivebranch,andwouldIpleaseruntheextractionroutine.Itwasallabit
Sparrow—One Week in Heron City (Case B) | 7
hush-hushforsomereason,andweweren’tsupposedtotalkaboutit.Thisseemsreally
oddtome.It’snotjustthatdataanalysisisn’tdonehere.Ialmostgettheimpressionit’s
prohibited.Likewe’dgetintolegaltroubleifweactuallyusedthedataforanything!
Anyway,Ididthedumpforhim.ButIbetthecontractorsdidn’tdothejobright.
Chief Harrison: Whatdoyoumean,“Didn’tdothejobright”?
Nigel Jewett: Theydon’tknowthedata.Dotheyknowaboutthetranspositionerrors?Didtheycorrect
for them or allow for them in the analysis?
Chief Harrison: Idon’tknow.Doyouthinkan8-percent-errorratemattersmuchwhenyou’relookingfor
apatternofstalking?
Nigel Jewett: That’sactuallyratheraninterestingsubjectforscientistswhocareaboutpatternrecog-
nition.Somestructuresthatyoulookforfallapartprettyquicklywithadataerrorrate
ofonly1percentorso.Otherstructuresremainprettyvisibleevenwitherrorratesupto
50percent.Somepatternsyoucanseequiteclearlywithonly10percentoftherelevant
information.ButIhavenoideahowthisoutsidegroupapproachedtheproblemand
whatallowancestheymade.AndsoIdon’tknowhowrobustthesearchmethodthey
used would be in compensating for missing or bad data.
Chief Harrison: Yousaid“structures.”Whatdoyoumeanbythat?Likeadolphintravelingalone?
Nigel Jewett: Well,structuresarehigher-levelobjectsthanindividualitems,likeadolphinorasick
whale. You can search for structures of coincidence that ought not to be there. Or you can
searchforstructuresthatshouldbetherebutaren’t.Likeawholegroupofcommuters
notgoingtoworktoday.Thesearethefourmaingeneralclassesofthings-to-search-for
withinmassivedatabases:(1)known“bads,”(2)deviationsfromnormality,(3)presence
ofstructuresthatshouldn’tbethereand(4)absenceofstructuresthatshould.Whatever
thethingisyouareinterestedin,youfigureoutthedatarepresentation,thenyoucreate
an algorithm to search for it and to display the results in a form you can use, and then
you test the output to see if it means what you thought it meant. Then you go around
throughtherefinementloopseveraltimes,untilyou’vegotarobustalgorithm,showing
yousomethingyouwantedtoknow.
8 | New Perspectives in Policing
Chief Harrison: I’veheardthatword“algorithm,”butneverreallyunderstoodwhatitmeans.Infact,one
ofmyhusband’sbrothersdescribeshimselfasanalgorithmist.IknowheworksatLos
Alamoslabsand,lastIheard,hewasworkingoncredit-cardfrauddetectionforcredit
cardcompanies.Ithoughthewasacomputerprogrammer.Isitthesamething?
Nigel Jewett: Not really. You can represent an algorithm in a program, but you shouldn’t need to do any
programmingyourselfifyou’vegottherightkindofhigh-levelquerytools.Analgorithm
is simply a series of logical steps, in order, that get you the analytic product you want from
thedatayoustartwith.IuseExcelalot—simplespreadsheets—andwhateveryoudo
once,youcanrecordasamacro.Youdon’tneedtoknowanyprogramminglanguage.
Then,ifyouwanttorepeatthatanalysis,youjustcallthemacro.Onekey.Canbepretty
efficient.Theonlyproblemisthatyoucanonlystickamillionorsorecordsintoanyone
spreadsheet,whichisabitofalimitationforsomethings.So,forbiggerdatasets,Ihave
to use some other tools.
Chief Harrison: Whydoyousayyoucan’tdoanalysisoftheALPRdatahereintheITdepartment?
Nigel Jewett: That’swhatIwantedtotellyouabout,ma’am.Here,thesystemisrestrictedtotheuses
alreadydefinedinthecontractaheadoftime.Thesystemgivesalerts.Andapartfrom
thatitjuststoresthedata.There’snofacilitytosliceanddiceorplayaroundwiththe
data. The contract was set up on the assumption that they could predict, ahead of time,
everythingthey’deverwanttodowiththedata.That’scrazy.Nooneeverknowsthatup
front.
Chief Harrison: Soyoucan’thuntfordolphinstravelingalone?Orforanythingelseofinterest?
Nigel Jewett: Well,Ican.That’sthepoint.Butnothere.Andmybossisonlyinterested,unfortunately,
indataquality.IfItrytopokearoundanddosomethingusefulwiththedata,likefigure
outwhat’shappeningtothestolencars,notonlydoIhavetomesswiththeoperating
system(andpotentiallyupsetthevendor)butIalsodon’tkeepupwithmyworkload
schedule,whichalreadytakesmesevenhoursadayattheworkstation.Andapparently
it might be frowned upon, legally, as well.
Chief Harrison: Sowhatdoyoudo?
Sparrow—One Week in Heron City (Case B) | 9
Nigel Jewett: WhatInormallydoisgetbored,andmyeyesgetsore.WhatIdidthistimeis,Itooka
copyofonemonth’sdata—theextractIwasaskedtorun—andtookithomewithme.
OnmyUSBstick,25gigabytes.Nottheimages,ofcourse;thatwouldbewaytoomuch
data.Justtheextracteddata.MaybeIshouldn’tbetellingyouthis!
Chief Harrison: Whyonearthdidyoutakeithome?
Nigel Jewett: SoIcouldloaditontomycomputerandusemyowntoolsandmacros.I’vebuiltupa
prettyusefulcollectionofthemovertime.Thesystemdumpcomesoutinasortofflat-
file,comma-delineatedformatandyoucanreadthoseintoExcelifyouknowwhatyou’re
doing.Youhavetostripoutawholebunchofspuriouscharactersandsoon.Butyoucan
getthedatainaformyoucanshuffle,andfilterandcarveup.So,thenIcoulddivedown
into the data and swim around a bit.
Chief Harrison: And what did you see?
Nigel Jewett: Ithinkyou’vegotthreedifferentstolencarproblems.Notjustone.
Chief Harrison: Whatdoyouthinktheyare?
Nigel Jewett: Firstofall,there’stheordinaryjoyriding.Seemstobeoldercarsonthewhole.They
mostly stay within the city. They’re found — according to the stolen car report data in
the system — within a day or two. And damage seems to be minor and miscellaneous.
Notdeliberatevandalismoranythinglikethat.
Chief Harrison: OK.That’snotthepiecethateveryone’sbaffledbyatthemoment.Whataboutluxury
cars?
Nigel Jewett: That’sthenextpiece.Ifyoufilterouttherecoveredcars,andrankordertheremainderby
reportedvalue,thenthetop100casesaredominatedbythreemakes:Lexus,BMWand
Mercedes.
Chief Harrison: Yes,weknewthat,Ithink.Butwhyaren’twegettingalertsonthese?Don’ttheygopast
theALPRlocations?
10 | New Perspectives in Policing
Nigel Jewett: Yes, they do. The reason you don’t get alerts is because they haven’t been reported stolen
atthetimetheygopasttheALPRs.Theyaretypicallyreportedstolentwotothreehours
afterthelastALPRsightingwithinourarea.
Chief Harrison: Soyouthinktheownersaredrivingthemawaysomewhere,andreportingthemstolen
later?
Nigel Jewett: No.Itisnottheowners.Ilookedatthestolen-fromlocations,andtheyseemtobedif-
ferentparkinglots,spreadallovertown.Buttheyareallconnectedtosimilartypesof
establishments.
Chief Harrison: Likewhat?
Nigel Jewett: Cinemas.Restaurants.Theaters.Parkinglotsinthetheaterdistrict.Theseareallplaces
whereyouknow,whenacararrives,thattheownersaregoingtobebusyforatleasttwo
hours.Watchingamovie.Havingtheirmeal.Whateverthey’retherefor.Which,Ithink,
gives the thieves time — assuming they watch the car arrive and steal it right away — to
driveitoutofourarea,andevenpastourALPRs,beforeitgetsreportedmissing.
Chief Harrison: Smartenough.Soyouthinktheyaretargetingnotonlyparticulartypesofvehiclesbut
patronsofparticulartypesofestablishmentjusttocutdowntheriskofalerts?Canyou
see where they are going?
Nigel Jewett: Ithinkthisisatheft-to-orderoperation.Theheaviestconcentration,intermsoftime,is
WednesdayandThursdayevenings,between7and10p.m.Thosearethetimesofthe
lastALPRsightings,withinourarea,ofluxuryvehiclessubsequentlyreportedstolen
butreportedthesamenight.Ihaveagraphofthesetimesforthatdefinedsubset.The
spikesareobvious.Andwherearetheygoing?ThelastsightingsarenearlyallonI-572,
southboundforMaynard.
Chief Harrison: Howcomewe’renotgettingrecoveriesfromMaynard?Doyouthinktheydon’tstayin
Maynard?
Nigel Jewett: Idon’t.There’sacontainershipthatleavesfromMaynardeveryFridaymorningforRio
deJaneiro.Ithinkthey’rebeingshippedoutonthat.
Sparrow—One Week in Heron City (Case B) | 11
Chief Harrison: Howonearthdoyoumakethatconnection?
Nigel Jewett: Ifigureditmustbeorganized.Thecoincidenceswerejusttoomanytobeisolatedcriminal
actions.Thisisoneofthosestructuresthatshouldn’tbethere.Itshowsthatthisisnot
arashofisolatedcrimes.AndwhenIsawtheI-572connection,Iwonderedaboutthe
portandwonderedwherethemarketwasforallthesecars.SoIGoogled“Lexus,BMW,
Mercedes,”justtoseewhatwouldcomeup.
Chief Harrison: And what came up?
Nigel Jewett: Thatwashopeless.Ahugelistofcardealerships.So,thenItriedthesamethingwith
“secondhand.”Samething.Hopeless.ThenItypedinthethreemakeswith“wholesale,”
andIstartedgettinghitsonalotofpartsdistributorsinLatinAmerica.Apparentlythere
isarealclamorforparts,forthesecarsinparticular,alloverLatinAmericaandBrazilin
particular.Ithinkthesecarsareworthafortunechoppedupintoparts.Notwhole.So
it’sawholesaleexportoperation,inparts,andweshouldprobablytalktoCustoms.
Chief Harrison: All this analysis … is this the type of analysis that criminologists do? Or do you marine
biologists have your own approach?
Nigel Jewett: Ithinkthecriminologistsandsocialscientistsworryalotmoreaboutstatistics,andregres-
sions,andthingslikethat.I’mactuallynotverygoodatthatstuff.Ifailedstatsincollege
andwasthereforenotallowedtotaketheregressioncourse.Iwasneverreallycomfort-
ablewiththeideaofrandomnessanyway.OrmaybeIjustwasn’ttaughtprobabilitytheory
particularlywell.Butthat’snotthetypeofanalysisscientistsdoverymuchanyway.When
you’restudyingnaturalsystemsandtryingtofigureouthowtheywork,yougoatitwitha
much more open mind. You don’t assume one particular analytic method is going to show
youanything.Youkeepanopenmindaboutthenatureofthething,andthestructure
underneath. You have to get under the covers, down in the weeds, and see what you see.
Thenyoucanworryaboutmodelsandtheories,andpickandchoosemethodsthatmight
actuallymakesenseandarebasedonwhatyou’veobserved,andsoon.Butatamuch
lowerlevel.Allthestuffthatreallycountsisbeneaththesurface.Andyouhavetofindit
first,andlookatit,andunderstandwhattypeofthingeachoneis.
Chief Harrison: Isthatlike“findingdistinctsubcomponentsofacrimeproblem,andstudyingtheirunique
characteristics,”likeHermanGoldsteinsaid?
12 | New Perspectives in Policing
Nigel Jewett: Ratherthanassumingacrimerateisjustacrimerate,andtreatingitasifitwerejustone
genericthing?Yes.Ihaven’theardofGoldstein.Butthatdoessoundexactlyright.
Chief Harrison: Whydon’tyouuseregressionanalysissincecriminologistsseemtouseitallthetime?
Nigel Jewett: Yes,theydo.Andeconomists,andsocialscientists.Butthat’sbecausetheyfocusona
veryparticularsetofmodelsortheoriesabouthowtheworldworks.And,onthewhole,
Idon’tthinktheworldworksthatway.Mostproblemsaren’tjustonethingoroneobject,
dependentonabunchofhigh-levelfactors.Thatseemstobethebasisformostregres-
sionanalyses.Mostproblemshaveatexturebeneath,andalotofpartsandpieces,and
eachofthoseseparatecomponentsallbehavequitedifferently.Andtofigureouthow
the natural world behaves, you have to dive down among the parts.
Chief Harrison: And swim around?
Nigel Jewett: Yes,ma’am.Swimaround.Seewhatthereistosee.Enjoythecolorsandthespectacle.
Chief Harrison: Andwatchoutforthesharks.Andstingrays.What’sthethirdpiece,bytheway?
Nigel Jewett: Oh,newercarsbutnotluxuryones.They’rebeingdriventosomespecificlocationsand
dumped.And,theyhavethebuilt-inGPS4 systems stripped out of them.
Chief Harrison: Nigel,thisisveryinterestingstuff.HaveyoulookedattheHayleyScottcaseatall?
Nigel Jewett: No, ma’am.
Chief Harrison: Doyouhaveherlicenseplatenumber?
Nigel Jewett: Icangetitfromtheregistryfiles,providedithasn’tbeenblocked.
Chief Harrison: Nomoretakingthedatahome,youunderstand?That’snotallowed.Encryptedornot.
Doesn’tmatter.Bringyourcomputerandyourmacrosinhere.Doyoustillhavethedata
for that one month leading up to the murder?
4 Global Positioning Satellite
Sparrow—One Week in Heron City (Case B) | 13
Nigel Jewett: Yes,ma’am.Onmydatastick.
Chief Harrison: Ihavetwojobsforyou.Canyouwriteupwhatyou’vetoldmeaboutthethreecomponents
ofthestolencarproblem?Lessthanfivepages.Justnotesisfine.I’llwantyoutocome
with me to the senior staff meeting Friday morning, if you can.
Nigel Jewett: Yes,ma’am.WhatIshouldsaytoMr.Goring?
Chief Harrison: Youshouldleavethattome.Theotherthingis,takeafewhours,ifyoucan,andseeifyou
canfigureoutifHayleyScottwasbeingfollowed.OK?
Nigel Jewett: Whichonefirst?
Chief Harrison: HayleyScott.
Nigel Jewett: OK.Bytheway,there’soneotherthingI’dbeinterestedtolookatsometime.
Chief Harrison: What’sthat?
Nigel Jewett: The accident rate in town.
Chief Harrison: Why?Itjustwentdownthislastmonthbyabout10percent,didn’tit?
Nigel Jewett: Yes,ma’am.Itdid.Butlastyearatthistime,itwentdownquitealotmore.Iremember
last year, seeing the press stories about how the police department was so proud of the
reductions,andIrememberthinkingitwastheendofthetouristseason,andtherate
oughttohavedroppedoffalot,justbecauseofthat.Thisyear,thedropisonly10percent.
Lastyear,itwasmorelike35percentmonthtomonth,ifIremembercorrectly.
Chief Harrison: Sure.Takealookifyouhavetime.ButHayleyScottfirst.
Wednesday Afternoon: Dr. Tom Boden, Compliance Monitor for Evidence-Based PolicingFollowingareexcerptsfromameetingbetweenChiefLauraHarrisonandDr.TomBoden.Dr.Bodenisa
criminologistwhohasbeenworkingwithintheHeronCityPoliceDepartmentfortwoyearstoadvancethe
useofevidence-basedpolicing.HeronCityisoneof18cities,spreadthroughouttheUnitedStates,Canada
14 | New Perspectives in Policing
andEurope,participatinginamajorinternationaleffortfundedbyaconsortiumofphilanthropicfounda-
tionstomoveevidence-basedpolicingfromtheacademicliteraturetotheworldofpolicepractice.Underthe
termsoftheprogram,eachcitygetsaqualifiedcriminologistworkingfulltime,onsite,foraninitialthree-
yearperiod.Dr.BodenwaspostedtoHeronCity,andhissalaryispaidfromgrantfunds.Thedepartmentalso
receivesagrantforaccommodatingandsupportingtheworkoftheircompliancemonitor.
Chief Harrison: Veryhappytomeetyou,Dr.Boden.Ireadoneofyourearlypapers,sometimeago,when
Iwasstudyingforoneofmypromotionexams.
Dr. Boden: Likewise,chief.Happytomeetyou.AndwelcometoHeronCity.I’mnotsureyourpre-
decessorandIalwayssaweye-to-eye.I’llcertainlydoeverythingIcantomakesurewe
makethisdepartmentjustaseffectiveasitcanpossiblybe.
Chief Harrison: Iappreciatethat.ButI’mcurious.Whatdoesyourtitle“compliancemonitor”actually
mean?
Dr. Boden: I’mnotsureIlikethetitleallthatmuch.Buttheideais“evidencecop,”orsomething
likethat.ItcomesfrompapersbyProfessorLarrySherman,andhesaystheroleofthe
evidencecopis“toredirectpracticethroughcomplianceratherthanpunishment.”Soit
isactuallysupposedtosignifyacloseworkingrelationshipasopposedtoanadversarial
one.Isupposeitcouldsoundasif“compliancemonitor”meantsomethingadversarial,
butthat’snotthewayIinterpretit.
Chief Harrison: I’mhappytohearthat.Because,Imustsay,Ifindtheideaofanacademicresearcher
“redirecting”apolicechief—eitherthroughpunishmentorcompliance—ratheramus-
ing.Butwhosecompliancearewetalkingabout,justsoI’mclear?Mine,Isuppose?
Dr. Boden: No,ma’am,notyours.Itisaboutthedepartment’suseofvariousmethods.Thewhole
ideaistomovethedepartmentfromchoicesbasedonassumptionsandguesswork
towardchoicesandmethodsbasedonfactsandproventoworkthroughtheuseofproper
scientificmethods.
Chief Harrison: Whatkindofscientificmethods?
Dr. Boden: Empiricalresearch.Theideaisthatpolicingshouldbeassolidlygroundedinscientific
researchasthepracticeofmedicine.Sowe—andwhenIsay“we,”Imeanthecommunity
Sparrow—One Week in Heron City (Case B) | 15
ofprogram-evaluationexpertswhoareparticipatinginthisprogram—useonlythevery
best studies, and even then we normally require that there be at least two or more studies,
in different locations, that show a program to be effective before we accept that it really
is.Notjustanystudieseither,butstudiesofthehighestquality.
Chief Harrison: OK.Butwhatmakesonestudyofhigherqualitythananother?Andwho’stojudge?
Dr. Boden: Well,alotofworkhasbeendoneinthatarea.Themostreliableevidencecomesfrom
randomized controlled experiments, where you can really isolate the effect of an inter-
vention.Someformsofquasi-experimentaldesignrankprettyhighly,too,providedthe
researchersinterpretingthemknowaboutanddealwithalloftherelevantinference
problems.Intermsofjudging,wearemovingtowardafairlybroadinternationalagree-
ment about how many studies you need, and of what quality, before the effectiveness of
a particular program should really be accepted.
Chief Harrison: Soundslikeaprettyhighstandard!Andalotofwork.Howlonghasthisbeengoingon?
Bytheway,howmuchpoliceexperiencedoyouhave?
Dr. Boden: I’veneverworkedasapoliceofficer.ButIhaveworkedonpolicedataandcrimedataever
sincemyPh.D.Mythesiswasontheimpactoflead-paintexposureinearlychildhood
anditssubsequentimpactsondelinquency.Weknowthistypeofresearchtakesalong
time, and one of the ways we are trying to accelerate the process is by reviewing stud-
ies already completed by others and, if they’re done well enough, we can combine their
findingsthroughmeta-analyses.Thatgivesusevenmorerobustfindingsandsavesthe
need to set up brand new experiments.
Chief Harrison: Whatkindsofprogramshaveactuallypassedthistest?Andhowmanyofthemare
there now?
Dr. Boden: TheNationalCrimePreventionCentre,inCanada,publishedasummaryin2007.They
listed14typesofprogramsthatcouldnowbeaccepted,thatis,proveneffectiveinpre-
venting crime.
Chief Harrison: Just14?Canyougetmethatlist?I’dlovetoknowwhattheyare.
16 | New Perspectives in Policing
Dr. Boden: Ihaveithereinmycase.[Handsoverdocument5 and points to listing on page three.]
Chief Harrison: Isee.Sofamily-basedpreventionisonecategory,andthatcategorycontainsfiveapproved
programs.Isthatright?Includinghomevisitation,daycare,parenttrainingwithyounger
childrenandsoon.Thesedon’treallysoundlikepolicebusinesssomuch.
Dr. Boden: Yes,ma’am.Buttheyarecrime-preventionprograms.Fiveofthemapprovedunderthe
family-basedpreventioncategory,threeundercommunity-basedprevention,three
underschool-basedpreventionandthreeunderplace-focusedprevention.
Chief Harrison: Whataretheplace-focusedones?Maybetheysoundmorelikepolicework.
Dr. Boden: Thesearetheplace-focused,crime-preventionprograms.[Hepointstodocument.]They
arenuisanceabatement,closed-circuittelevisionsurveillancecamerasandimproved
street lighting.
Chief Harrison: Soyouhavejust14programsintotalthatyou’veestablishedactuallywork.Isthat
right?
Dr. Boden: Ithinkacouplemorehavebeenaddedsince2007,butroughlythatnumber.Wecould
acceptmore,butweneedtokeeptheresearchtothehighestpossiblestandardssowe
don’tmakemistakes.Thewholeideaistodirectpublicfundstothoseprogramsthatwe
knowforsuremakearealdifference.TheCanadiansusedaveryhighstandardforthis
listing.Theysayhere,onpagefive,thataswellasusingproperexperimentalorquasi-
experimentaldesigns,thestudiesshouldalsoinclude“largesamples,longfollow-up
periods,follow-upinterviews,andprovisionforeconomicanalysis.”6
Chief Harrison: IfIhadtoguess,I’dsaythatthisdepartmentprobablydoesatleastathousanddiffer-
ent things each day, all supposed to contribute to crime prevention. Are you saying we
shouldn’t be doing the other — however many it is — 986?
Dr. Boden: Well,theselistedherearemajorcrime-preventionprogramsthatarerunacrossbroad
segmentsofthepopulation.Notjustordinarydailydecisions,likewhatthebeatofficer
shoulddonext.Thisisdesignedtohelppoliceandsocietymakethebigcrime-prevention
investmentsonthebasisofscienceratherthanguesswork.
5 See appendix: Evidence-Based Crime Prevention: Scientific Basis, Trends, Results and Implications for Canada, by Brandon C. Welsh. 6 Ibid., p. 5
Sparrow—One Week in Heron City (Case B) | 17
Chief Harrison: Istherereallynothinginbetween—betweenyourkindofscienceandguesswork?It
sounds as if it has to be high science, complete with enormously expensive randomized
experiments,armiesofPh.Dsand,Iassume,ahugeamountofmoney.Andifit’snot
that,thenit’switchcraft,ormaybejuststupidity?Don’tpolicemanagersdoanawfullot
of perfectly sensible stuff that you haven’t even had a chance to consider yet? And don’t
theyconfrontproblemsthatnobody’sseenbefore,wheretheyjusthavetotrywhatseems
bestatthetime?Howlongdoesittake,fromthetimeanewproblemappearstothetime
thatyourcommunityofscholarsactuallydecideswhatworks?Mustbeagoodfiveyears
orso?Whathelpisthatforoperations?
Dr. Boden: It’ssurelybettertoknowwhatworks.Otherwise,we’djustkeeppouringpublicmoney
down the drain.
Chief Harrison: Don’tyouthinkpoliceknowanythingwithoutyourhelp?Hey,waitaminute.I’mlooking
atthislist.DoyouknowwhatIdon’tseehere?Catchingmurderers.Doyouthinkcatching
murderersisimportant?Ifwecontinuethisveryhigh-profilemurderinvestigationthat
wehavenow,whichistearingupourcityatthemoment,willIgettobe“noncompliant”
inyoureyes,justbecausearrestingmurderersdoesnotappearonthislist?Haveyou
evaluatedcatchingmurderersyet?Whataboutmeetingwiththemayor?Canyoutellme
theoptimalnumberoftimesIoughttomeetwiththemayorpermonthtoreducecrime
tothelowestpossiblelevels?Doyouhaveequationsforthat?
Dr. Boden: Wehaven’tlookedatthosethings.No.Amurderonlycountsforoneinthereportedcrime
figures.Itprobablywouldn’tfigureverymuchinthetypesofanalysiswenormallydo.
Chief Harrison: So,whatmakesthings“figure”inyourtypeofanalysis?Publicoutrage?Politicalpres-
sure?Dreadfulfearwreckingpeople’slives?What?
Dr. Boden: The things that matter in our analyses generally start off as factors or programs that end
upwithastatisticallysignificantcoefficientinaregressionanalysis,orasignificanteffect
under hypothesis testing of some sort. The dependent variable is usually the crime rate or
somepieceofit.Econometricmethodspointustothefactorsthatreallymakeadifference.
Andthen,whenwearereadytoevaluateaspecificprogram,wetrytosetupaproperly
constructed experimental design so we can measure the impact on crime rates of a spe-
cificinterventionandbereallysureitistheintervention,andnotsomethingelse,thatis
makingthedifference.That’sthestagewhenwetrytoestablishacausalconnection.
18 | New Perspectives in Policing
Chief Harrison: Alright.Justsoyouknow,Ineverdidaregressionanalysisorranarandomizedexperi-
mentinmylife.AndI’msorryyoudon’thaveastudy,orhaven’tdoneone,thatshowsthat
investigatingmurdersisactuallyimportant.ButI’mgoingtoseethatmurderinvestiga-
tionthroughanyway,ifthat’sokaywithyou.
Dr. Boden: You don’t need my permission, ma’am. You’re the chief.
Chief Harrison: Thismakesmewonder.Maybeyourrole,withallthissophisticatedresearchatyour
disposal,shouldbetoinformmeaboutthingsthatmightworkandthatIwouldn’thave
thoughtofbymyself.Howaboutthat,asabasisforourrelationship?Iguessthatmight
seem more reasonable to my operational managers than the idea that you’d prohibit
themfromdoingthingsjustbecausescholarshiphadn’tgotaroundtoevaluatingthem
yet.Butletmeaskyouonemorething:HaveyoureadGoldstein?
Dr. Boden: Yes, ma’am. Of course.
Chief Harrison: Doesn’tGoldstein’sapproachsuggestthatweshouldtackleproblemsonce,makingsure
thatwedeviseasolutionthatnotonlysuppressestheminaneffectiveandresource-
efficientmannerbutalsokeepsthemsuppressedforagoodlongtimeandwithminimal
subsequent effort?
Dr. Boden: Yes.Iguessthat’safairdescriptionoftheproblem-solvingapproach.
Chief Harrison: Itstrikesmethatthisveryshortlistofprogramsthatyouandyourcolleagueshaveactually
approvedforusebypolice—suchasdaycare,orafter-schoolrecreation—arepro-
grams that once you’d started, you’d probably continue forever and at enormous expense.
Presumablyyouhavetocontinuetheseprogramsallthetime,onceyou’vestarted,and
foreachsuccessivecohortandeachgenerationofmight-bedelinquents.Isthatright?
AreyouandGoldsteintalkingaboutthesamekindofapproach?
Dr. Boden: Well,theclosestthingtoGoldstein’sideathatmostpolicedepartmentsactuallydois
place-basedpolicing.Policetendtodohot-spotanalysesandplace-basedinterventions.
Sowehaveevaluatedsomeofthosemethods,andthat’swhysomeoftheseplace-based
ideas,likecamerasandstreetlighting,appearonthislist.Thenuisanceabatementidea
islinkedcloselytothebrokenwindowstheory,andthat’sbeenprettywellvalidatedover
theyears.SowebelievewehavevalidatedGoldstein’sapproach.
Sparrow—One Week in Heron City (Case B) | 19
Chief Harrison: SoyoutestedGoldstein’sapproachbyfindingoutthatplace-basedproblems,likehot
spots,tendtohaveplace-basedsolutions.Isthatright?
Dr. Boden: Webelievethathasbeendemonstratedinenoughplacesnowsowecanbefairlysureit
works.Yes.
Chief Harrison: Isn’tthatratherobvious?Couldn’twehaveguessedthatplace-basedproblemswould
tendtohaveplace-basedsolutions?Doesn’tthelikelyshapeofthesolutiongowiththe
shapeoftheproblem?Imean,ifitwasafamily-shapedproblemratherthanageographic
hotspot,wouldn’tyouexpectafamily-centeredsolutionofsomesort?
Dr. Boden: Thewholepointisthatweshouldn’tberelyingonguesswork.
Chief Harrison: Bytheway,doesn’thot-spotanalysisbypolicepredateGoldstein?IthoughtGoldstein
startedoffbycomplainingaboutjusthownarrowthepoliceprofessionhadalwaysbeen
in the types of analysis they used. The police always did hot spot analysis, even when it
waswithpin-mapsontheofficewall.IrememberGoldsteinstartsoffoneofhisbooksby
listingabout13otherdimensionsinwhichweoughttobeabletoidentifyproblems:like
repeat victims, repeat offenders, modus operandi, criminogenic commodities, patterns
of organized crime and so on.
Dr. Boden: Ithinktheintelligence-ledpolicingsystemfollowsupontherepeatoffendersidea.And
wehaven’thadachancetoevaluatethatapproachyet.Thatoneisdifficulttoevalu-
atebecausedifferentdepartmentsactuallyimplementintelligence-ledpolicinginsuch
different ways.
Chief Harrison: ButwhathaveyouandyourfriendsdoneaboutGoldstein’sideas?Itsoundstomeasif
you’vetestedGoldsteinbytestingtheonethinghecomplainedaboutasbeingtheonly
thingthatpoliceknewhowtodo?IfIwasHermanGoldstein,Idon’tthinkI’dbethrilled
about that!
Dr. Boden: Ithinktheworkdoneonplace-basedapproacheshasbeenprettythorough.Prettyhigh
quality.Wecansay,forsurenow,thatsomeofthesemethodsactuallywork.
Chief Harrison: Fromwhatyousay,itseemstomeyou’vevalidatedsomeofthemostlimitedandsimple-
mindedformsofGoldstein’sapproach.Isupposeyoudohavetofocusonthemethods
20 | New Perspectives in Policing
thatenoughpolicedepartmentshaveused—likeimprovingstreetlights—andina
sufficientlystandardizedmannerthatyoucanactuallyperformyourmeta-analyses.
Soyouenduplookingatstandardizedtools,generallyunderstoodeverywhere.Didn’t
Goldsteintalkabouttailor-madeinterventionsforcarefullyidentifiedproblems?He
talkedalotaboutthefactthatrealproblemshaveuniquefeaturesand,fromwhatIread,
I’dsayhestressedthatyouhadtounderstandtheuniquenessofaproblemtohaveany
realchanceofsuccess.Idon’tthinkheassumedthatatleastthreeotherdepartments
musthaveusedthesamesolution,exactlythesameway,beforewecanknowanything
about effectiveness. He was all in favor of brilliant, surgical, locally invented interventions,
wasn’the?Isn’tthatwhattheannual“Goldsteinproblem-solvingawards”aresupposed
to celebrate?
Dr. Boden: Theevidence-basedtraditiondoesrecognizethatcontextsvary,andofcourseyouhave
totakethatintoaccount.So,onceaprogramisacceptedaseffectiveandapprovedforuse
in crime prevention, then we do understand that the program may need to be tailored,
tosomedegree,ifyoudecidetouseitinanotherjurisdiction.
Chief Harrison: Butyouhaven’tansweredmyquestion.Goldsteinstartswithproblems.Youstartwithpro-
grams.Goldsteinsaystheproblemsareoftenuniqueandrequirecarefulstudy.Healso
saysyoufirstneedtodisaggregatetheoverallcrimerateintoindividualandactionable
pieces.Isn’tthatwhattheydoinmedicine?Inevidence-basedmedicine,don’ttheystart
with a particular disease or condition? And don’t they also start with a careful description
orprofileofthepatient,withallofthepatient’sriskfactorsandhistory,andsoon?Isn’t
thatlikeGoldstein’sratherpreciseproblemdefinition,whichhesaysyoumustdofirst,
beforeyouevenbegintothinkaboutsolutionsormethodsorprograms?
Bycontrast,youseemtostartwithmethods.This[holdsupEvidence-Based Crime
Prevention]isalistofprograms.Shouldn’tIbelookingatalistofspecificproblemsfirst?
What’sthediseasethattheseprogramsaresupposedtocure?Idon’tseealistofproblems
here,exceptforcrimeingeneral.Maybedelinquencyingeneral.
Dr. Boden: I’llhavetothinkaboutthat,ma’am.Ithinkitismostlyadifferenceofsemantics.Ithink
we all want the same thing.
Chief Harrison: What’sthat?
Sparrow—One Week in Heron City (Case B) | 21
Dr. Boden: Tobescience-based.Forpolicingtobebasedonfacts.Notonsuperstition,orguesswork
oruselesstraditions.AndIdon’tmindifyou’dpreferadifferenttitle,somethingother
thancompliancemonitor.I’dbehappytothinkofmyselfasyourchiefscientistinstead,
ifthatmakessensetoyou.
Chief Harrison: Dr.Boden,I’mnotsureIneedachiefscientist.IthinkIjustneedsomesensibleanalysts,
whocanactuallyhelpmegetthejobdone.Let’ssee.CanyouhelpmesolvetheHayley
Scottmurder?
Dr. Boden: No.Idon’tthinkso.
Chief Harrison: Can you tell me what might prevent or reduce our rash of car thefts — brand new, luxury
class vehicles — and explain why they seem to be disappearing into thin air at unprec-
edented rates and only in this city? Can you offer any insight, from your studies, as to
where they might be going?
Dr. Boden: I’mnotawareofanyworkspecificallyontheftsofluxurycars.Iguessthethingthatmight
helpistousesomeoftheseplace-basedapproachesthathavealreadybeenproven.We
doknowthatCCTVactsasafairlygoodpreventivemeasure,althoughitdoesseemto
workbetterinEnglandandWales,forsomereason,thanitdoesintheUnitedStates.
Chief Harrison: [Laughs].MaybetheUnitedStatesisbigger,sothingsaremore spread out. Oh, excuse
me.I’monlyguessing.That’snotallowedanymore,isit?
Dr. Boden: Are these car thefts concentrated in hot spots at all?
Chief Harrison: Absolutely not, according to my chief of operations. They’ve been mapping them for a
good long time, and they seem to fall all over the city. There are many, many tiny clusters,
butnobigclusters.Therearealmostasmanyclusters,now,asthereareparkinglotsin
the city. And that’s several hundred. No way could CCTV coverage be affordable.
Dr. Boden: Wecouldcutthecostinhalf,ifyoulike.Wecouldputthecamerasupinhalfofthepark-
ing lots, rather than in all of them. Then we could really see what difference they made.
Mightbeareallygoodexperiment.I’dbeveryhappytohelpyouwiththeexperimental
design.
22 | New Perspectives in Policing
Chief Harrison: Any other ideas, apart from running experiments so you can get your name in print?
Dr. Boden: Whataboutimprovingthestreetlighting?That’sbeenshowntoworkinmanydifferent
cities.
[ChiefHarrisonlooksupbutdoesnotreply.]
Dr. Boden: Iguess,ifthethievesturnedouttobehighschoolers,thentheafter-schoolrecreation
programs might help?
Chief Harrison: ThankyouDr.Boden.Letmeshowyouout.Iappreciateyoucomingup.
ChiefHarrisonstartstoleadDr.Bodentowardtheofficedoor,buthalfwaythereshestopssuddenly,turns,and
(beingquiteaccomplishedinmartialarts)deftlystrikesDr.Boden’snosewiththebaseofherflat,openpalm.
Nothard,butaccurately,andjusthardenoughtomakehisnosebleed.Dr.Bodenlooksstartledandhorrified,
andfumblesforhishandkerchiefasbloodbeginstotrickledownhisface.ChiefHarrisonsmilesathimkindly
andhandshimaboxoftissuesthatwasontheedgeofherdesk.
Dr. Boden: Excuseme,ma’am.Whatwasthatabout?
Chief Harrison: Oh,I’msorry.Justamodestlittleinterventionofmyown.
Dr. Boden: You made my nose bleed!
Chief Harrison: No,no,Idon’tthinkso.JustbecauseItouchedyourfaceIdon’tthinkyoucanjumpto
theconclusionthatitwasIwhomadeyournosebleed.Onthecontrary,there’sastorm
coming,andIassumeitwasthedropinbarometricpressure.Maybeyoualwaysget
nosebleedsthistimeofdayorinthistypeofweather.Ireallydon’tthinkithadanything
to do with me.
Dr. Boden: Butyouhitme.Andnowit’sbleeding.It’sobvious.
Chief Harrison: Surelyyoucan’tpossiblydeduce,basedonjustasingletrial,andwithnocontrolsample
ofanykind,thatmystrikingyouactuallycausedyournosetobleed.Wouldthatkindof
claimmakeitthroughyourfiltersforhigh-qualityscientificevidence?OrtheCanadians’
Sparrow—One Week in Heron City (Case B) | 23
evenmorerigorousstandards?Wherearethelargesampleandtheextensivefollow-up
interviews?
[Dr.BodenlooksatChiefHarrison,bemused.Hemovestowardthedoor.]
Chief Harrison: IfwereallywantedtoknowforcertainthatImadeyournosebleed,wouldn’twehave
toconductasignificantnumberoftrials?Wecoulddothisagain.Isupposeitwouldbe
good if we could get some of the other compliance monitors also, to stand right next to
you.Andwe’dhitsomeofthem,butnotothers.Mayberandomselectionwouldhelp?
Whatdoyouthink?Shouldwedoarealexperiment?
Thursday Morning: Nigel Jewett, Junior Analyst, IT DepartmentWhenChiefHarrisonarrivedatherofficeat8a.m.onThursday,NigelJewettwassittinginthewaitingarea
outside.
Chief Harrison: Nigel, good morning. Come right in.
Nigel Jewett: Thankyou,ma’am.Thiswasfun.
Chief Harrison: Howlongdidittakeyou?
Nigel Jewett: Mostofthenight.ButIthinkitwasworthit.
Chief Harrison: Sotellme.Whatdidyoudo?
Nigel Jewett: Anumberofthings.Wedohaveanaccidentproblem.AndIdidsomeworkontheScott
case, too.
Chief Harrison: Whatkindofaccidentproblem?
Nigel Jewett: Thanks,first,forgettingmetheaccidentdata.OnceIhadthatinExcel,itwasprettyeasy
tofigureoutwhatwashappening.Ijustlookedtosee,monthbymonth,whatsegment
of the accident data was not following the aggregate trend downward.
Chief Harrison: And was there one?
24 | New Perspectives in Policing
Nigel Jewett: Yes.Itseemstobewomendrivingalone.Andnotalwaysalone,butwithnootheradult
inthecar.Sometimestheyhavetheirkidsinthecar.
Chief Harrison: And what’s happening to them?
Nigel Jewett: Theyjustrunintothings.Thecarinfront.Afewintotreesorotherobjects.Justseems
likethey’renotpayingattentiontotheirdriving.
Chief Harrison: So?Whatdoyoumakeofthis?Arethemenbeingequallycarelessallofasudden?
Nigel Jewett: No.Themen-drivingnumbersarebehavinglikeeverythingelse—droppingoffbytotal
volume.IthinkitmightberelatedtotheScottcase.Maybewehavejusttoomanywomen
worryingaboutbeingfollowed.Maybethey’reallspendingtoomuchtimestaringinto
theirrear-viewmirrors.That’stheonlyreasonIcouldthinkof.
Chief Harrison: Areyousureaboutthetrend?Iknowyoudon’tmuchcareforprobabilitytheory,butcould
thisjustbeafluke?Isthisstatisticallysignificantatthisstage?
Nigel Jewett: Probablynot.ButIthoughtyou’dwanttoknowaboutitbeforeitgottobestatistically
significant.Itisquiteaparticulargroupingofaccidents,onceyouseeit,anditincludes
two fatalities already this month. That’s twice as many as the murder itself.
Chief Harrison: WhatabouttheHayleyScottcase?Whathaveyoudoneonthat?
Nigel Jewett: Withherlicenseplatenumber...first,IranthesimpletestontheALPRdata.Itook30
secondsasthefollowingintervalworthchecking.IstartedwithHayleyScott’scarnum-
ber,atleasttheoneregisteredtoher,andsheshowsup403timesinthemonth.Imerged
thelistsforallthecarsthatpassedwithin30secondsafterwardsandlookedformultiple
hits.
Chief Harrison: And what did that show you?
Nigel Jewett: Notmuchthat’sinteresting.Herhusband’scarjumpsout,followingherseventimes.And
therearelotsofcarsthathitthreetimes.Butnofours.
Sparrow—One Week in Heron City (Case B) | 25
Chief Harrison: Thatmarriesupprettymuchwithwhatthecontractorfound,Ibelieve.
Nigel Jewett: Iftherereallywasastalker,andonlyone,thenI’dexpecttobeabletofindthemmuch
morecleanly.I’dexpecttofindawayoflookingatthedatatomakethemreallystickout,
if they were there at all.
Chief Harrison: Soyoudidn’tstopthere,right?
Nigel Jewett: No,ma’am.Ididacoupleofotherthings.Thefirstwastoallowfortheerrors.HayleyScott’s
numberisDBR862.SoIalsowantedtotryallofthemisreadingpossibilities.Thatcould
bereadas882,or682or662.Soonethingwastobroadenthesearchandcoverallfour
possibilities.ThatbumpedupthenumberofHayleyScottsightings,potentially,to432.
Chief Harrison: Whatelse?
Nigel Jewett: ThenIwonderedaboutthehusband.Notasasuspectsomuch.Butwhatwasittheywere
doing?Seventimeshewasbehind,andfourtimeshewasinfront.Butstillcloseinfront.
SoIwonderedwhatthatmeant.Ifthiswasmywife—andIdon’thaveoneyet—butifI
didandshethoughtshewasbeingfollowed,I’mprettysureI’dfollowrightbehind,notin
front.Soiftheyweredoingthat,itmeanstheyswapcarssometimes.Whichmakessense,
ifyou’vegottwodifferentsizesofcar.Dependswho’scarryingthetrashtothedump,or
who’sdrivingthekidsaround,right?SoIwonderedwhathappensifweassumeshealso
drives her husband’s car around town on a regular basis. And his car shows up 320 times
in the month.
Chief Harrison: Sonowyoucombineallthesethings?
Nigel Jewett: Exactly.Husband’snumberdoesn’thaveanysixesoreights.SoIdecidedtotreathis
number, and all four of her possibilities, as a single entity and see who might be follow-
ingthatentity,whicheveroneofthefiveformsittook.Thatgaveme432plus320,which
is752possibleHayleyScottsightings.Imergedthoselistsandstuckto30secondsfor
theinterval.TheScotts’owncarscomeupamongstthefollowers,asyou’dexpect,with
scoresofnineand13occurrences,followingbehindtheother.Ijustignoredthose.There
was still a big pool of threes. And a single car with a score of nine.
26 | New Perspectives in Policing
Chief Harrison: Nine?Sowhatexactlydoesthatmeanforthisonecar?
Nigel Jewett: ThatoneisloggedasbeingclosebehindHayleyScott’scar,asDBR862,twiceinthemonth.
Itisbehindhercar,whenherplateisreadasDBR882,threetimes.Iguessshehadadirty
licenseplate.Anditisloggedasbehindherhusband’scarfourtimes.It’senough.Itsticks
outlikeasorethumb.Thenexthighestscoreisthree.Thisisnine.
Chief Harrison: Doyouhavethenumber?
Nigel Jewett: Yes,ma’am.[Hepassesoveraspreadsheetprintoutwith18rowsshowingtheninesight-
ingsandninerelated“followings.”]Icouldhavetakenthisonelevelfurtheranddone
thepotentialcorrectionjobforallothercarshavingsixesoreights,or“I”sor“1”sintheir
plates.
Chief Harrison: How would you have done that?
Nigel Jewett: Iwouldhavecreatednewrecordsforallofthepossiblemisreadingsforallcarsinthe
database.Actually,Ididcreatethemacrosforthat,inExcel.Butitwasn’tnecessaryand,
in this case, it probably wouldn’t change the result.
Chief Harrison: Whynot?
Nigel Jewett: Becausethevehiclenowofinterestdoesn’thaveanyofthosecharactersinitslicense
plate.PYN447.Soyouwouldn’tincreasethescore.Andthattypeofcorrection—putting
backinpotentiallymissingdata—canonlyincreasethescoresifyou’reusinganykind
ofadditivescoringfunction,likeIwashere.
Chief Harrison: Thisisprettyimpressivestuff,Nigel.Soundslikeacomplicatedprocess.Asalgorithms
go, was this a tough one?
Nigel Jewett: No,notreally.Usuallyittakesawholesequenceofstagestogettoanythinguseful.We
callthese“multipassalgorithms”or“multistage”ones.Whatcomesoutofeachstageacts
asthestartingpointforthenextstage.Youfilterthisway,thensortthatway,thenscore
whatyousee.Andthen,usuallyyoudon’tknowwhattodonextuntilyoustareatwhat
youhave,atleastforawhile.Soyoucan’tspecifythewholeprocessupfront.That’swhy
Sparrow—One Week in Heron City (Case B) | 27
youneedthekindsoftoolswhereyoucanseewhatyou’redoingandwhatyou’regetting,
andwhyyoutryalotofdifferentideasprettyquicklyuntilsomethingjumpsoutatyou.
Chief Harrison: Whatmakessomeonegoodatthiskindofresearch?
Nigel Jewett: Mymarinebiologyprofessorusedtosay“abandoninguselessalleywaysquickly.”You
know,getoutofthemandintoanotherone.Nottoofast,ofcourse.Butnottosticktoo
long to any one analytic idea when it is not showing you anything useful.
Chief Harrison: Nigel,listentome.Thankyouforthis.Thismayturnouttobeveryimportant.ButIhave
61otherwomennowwhoareworriedtheyarebeingfollowed.Maybebythissamecar,
PYN447.Maybebyanotherguy.Maybebynobodyatall.Canyoudothisoveragain,61
times,foreachofthem?Didyousaveyourmacros?
Nigel Jewett: Iwasthinkingaboutthat.Yes,ofcoursewecandothesamethingfor61othernumbers.
Butthat’snotthebestthingtodo.
Chief Harrison: Whynot?Whatwouldyoudo?
Nigel Jewett: Whynotaskthebiggerquestion?Isanyonefollowinganyone?Maybepoliceoughtto
knowifanyoneisfollowinganyone.Maybesomeone’sbeingfollowedandisthenext
murdervictimandhasn’tevenbecomesuspiciousyet.Wouldyouwanttoknowthat?
Chief Harrison: You could do that?
Nigel Jewett: Ithinkso.Thereisoneextradifficulty,though,whenyoudon’thaveanyparticularplace
tostart,likeasuspectoravictim,andyouhaveverylargedatabases.Youhavetothink
carefullyaboutallthepermutationsandcombinationsyouneedtotry.AndIcheckedthe
volumesoverall.Wehaveroughly300,000uniquecarseachday,withmultiplesightings
ofmostofthem.Inamonth,closeto2millioncarsseenatleastfivetimeseach.Ifyou
startedwithjustthose2million—leavingoutthedrive-through-onceset—thenyou
wouldwanttoknowtherelationshipbetweenanyoneofthose2millioncarsandany
other one of those 2 million cars. You’d want to see which pairs have the most frequent
linksbetweenthem.You’ddefinetwocarsas“linked”iftheypassedanyALPR,anytime,
lessthansomanysecondsapart.Theintervalisasearchparameteryoucouldadjust,if
you needed to control the volumes of the output or change the sensitivity of the search.
28 | New Perspectives in Policing
Chief Harrison: Logically,thatsoundsalotsimplerthanwhatyou’vealreadydoneinthiscase.
Nigel Jewett: Logically,itis.Butcomputationally,itisn’t.Youmightstartoffwithamatrixorarray,2
millionby2million,andstartloggingthelinksinthearray.JustworkthrougheachALPR
historyonebyone,creatingallthelinks.Thencountthemupandlookatthebiggesttotals.
Butonmostmachines,unlessyouhavemassesofinternalmemory,youcan’tdeclare
arrays2millionby2million.Andifyoucan,youcan’tdoanythingwiththem.Itispretty
easy to blow up your machine, not literally of course, but grind it to a miserable halt by
writing a thoughtless algorithm that will produce billions and billions of possibilities.
Chief Harrison: Sowhatcanyoudo?
Nigel Jewett: For those types of problems, you have to get crafty and creative about the actual search
methodevenafteryou’vealreadydecidedwhatyou’relookingfor.Soyoufindwaysto
chopouthalfofthedata,hopefullywithoutloss.Ortolookfirstamongsubsetsathigher
risk.Andifthestructureyouwanttofindisoneofthosethatisnotatallrobusttomiss-
ingpiecesofdata,thenyousimplycannotthrowanythingawayor,forallyouknow,the
patternmightevaporatebeforeyoucanfindit.
Chief Harrison: So,whatthen?
Nigel Jewett: Forthose,youhavetouseothercomputationaltechniques,likesparsematricesand
linked-listprogramming,thatcutdowntheamountofmemoryspaceyouneedbywork-
ing only with the nonzero entries. Or use massively powerful computing technologies.
LiketheyhaveatLosAlamos,Iguess!Iwonderhowmanycredit-cardtransactionsthere
areeverydayontheglobalsystemsandwhatstructuresyourbrother-in-lawendsup
searching for. That must be fun, too!
Chief Harrison: Nigel,I’mintriguedbyyourideaoffun.I’dlikeyoutodomoreofthistypeofwork.Ijust
havetofigureoutwheretoputyouexactly,andhowthistypeofworkfitsinwithallthe
other things we have to do here.
Thursday Afternoon: Telephone Call With Dr. Tom Boden, Compliance Monitor for Evidence-Based PolicingFollowingareexcerptsofatelephonecallplacedbyChiefHarrisontoDr.TomBodenat2p.m.onThursday.
Sparrow—One Week in Heron City (Case B) | 29
Chief Harrison: Dr.Boden.I’mhopingwecanworkcloselytogether.AndIpromisenottoslapyourface
anymore.
Dr. Boden: Ma’am.I’mdelightedtohearthat.Ihopeso,too.
Chief Harrison: I’minterestedinsettingupanewanalyticalunittosupportoperations.I’mnotsureif
it’sthetypeofthingyou’dliketodo,orwhetheritservesyouragenda.ButIwouldneed
sometechnicallyverywell-qualifiedpeopletorunitandworkinit.
Dr. Boden: I’mhonored.Itsoundslikeagreatidea.ItisexactlythetypeofengagementIhadhoped
forinthisdepartment.Whatsortofstaffdoyouhaveinmind?
Chief Harrison: PeoplelikeNigel.DoyouknowNigelJewett?
Dr. Boden: Yes,IknowNigel.
Chief Harrison: Couldyouworkwithhim?Andpeoplelikehim?Maybewecouldgetsomeofhisfriends
or friends from college in here, too?
Dr. Boden: I’mnotsurethat’swhatyouneed,ma’am.Iactuallydon’tthinkNigelisqualifiedtobe
an analyst.
Chief Harrison: No,whynot?Whatmakesyousaythat?Heseemsquitebrighttome.
Dr. Boden: Maybe.Buthedoesn’tknowthefirstthingaboutprogramevaluation.
Chief Harrison: OK,Iunderstand.Thanks.Don’tworry,I’llfindsomeoneelse.
Dr. Boden: Ma’am,I’dbehappytohelpyoufindsomeoneelse.Icouldbringinsomereallygood
graduate students who would be really good for the department. And they’d be well
qualified.Verywellqualified,Icanpromiseyou.
Chief Harrison: Idon’tthinkyouunderstoodwhatImeant,Dr.Boden.I’mkeepingNigel.
30 | New Perspectives in Policing
Friday Morning: Nigel Jewett, Junior Analyst, IT ServicesAt10a.m.onFriday,NigelJewettcomestothechief’sexecutivesuiteandasksthechief’sexecutiveassistant
if he can see Chief Harrison. Nigel says it is urgent. Following are excerpts from his subsequent conversation
with the chief.
Nigel Jewett: I’verunit.
Chief Harrison: You’ve run what?
Nigel Jewett: Who’sfollowingwhom.Ifoundawaytodoitonmycomputer.Andmycomputerisnow
inmyoffice,ma’am.Ithoughtyou’dbepleasedtoknowthat.Iactuallyhadtoprogram
itinC++usinglinkedlists.Butitworked.
Chief Harrison: So,who’sfollowingwhom?
Nigel Jewett: There are three women. They are all being followed by the same car, but on different days
oftheweek.Onlyoneofthemisinthegroupof61thathavereportedanythingodd.The
other 60, by the way, have nothing to worry about.
Chief Harrison: Thesamecarasyoufoundformetheotherday?Wearrestedthatguyasasuspect!
Nigel Jewett: Notthatone.Anotherone.Butthesamecarforallthreewomen.Andthat’snotall.
Chief Harrison: Heavens.Whatelse?
Nigel Jewett: You’re being followed.
Chief Harrison: I’mbeingfollowed!Bywhom,forheaven’ssake?
Nigel Jewett: Twocars.Theyworktogether.Normallythere’soneinfront,close,within15seconds,and
onebehind,thatcanbeupto45secondsbehind.Theyswitchplaces,too.It’snotalways
the same way around.
Sparrow—One Week in Heron City (Case B) | 31
Chief Harrison: Whichcararetheyfollowing?
Nigel Jewett: Yourofficialcar,sometimes.Butmoreoftenyourprivatecar.Eveningsandweekends.
Thisgoesbackthreeweeks.Itstartedtwoweeksbeforeyouarrivedhere,ma’am.
Chief Harrison: Butaftermyappointmentwasannouncedinthepress,right?
Nigel Jewett: Isupposeso.
Chief Harrison: Whoisfollowingme?
Nigel Jewett: One car is private but registered to a lieutenant in the department. And the other is an
unmarkedcarregisteredtotheDrugSquad.
Chief Harrison: Who’dhavethoughtit?
Nigel Jewett: [Pause.]It’sfunnysometimes,whatyoudiscoverbyaccident.LikeMarieCurie.When
shediscoveredradium,shewasn’tlookingforit,oranythinglikeit,atall.
Chief Harrison: Butshewaslooking,andshewasascientist.Sosheknewhowtolook.Whoknows,maybe
she was having fun, too!
Nigel Jewett: Whywouldtheybefollowingyou,ma’am?
Chief Harrison: That’sanyone’sguess,atthispoint.Maybewefoundsomesharks,andweweren’teven
lookingforthem.TheyprobablywanttoknowifandhowImightbecompromised.
32 | New Perspectives in Policing
EVIDENCE-BASED CRIME PREVENTION: SCIENTIFIC BASIS, TRENDS, RESULTS AND IMPLICATIONS FOR CANADA
The State of Science on What Works to Prevent Crime
Research on “what works” in preventing crime has long been of interest to practitioners, policy-makers, and academics alike. Only in recent years, however, has there been an increased effort to improve the trustworthiness of claims about what works in preventing crime. This has come about through the use of the highest quality scientific evidence and the most rigorous and transparent review methods to assess what works. It has come to form the state of science on evidence-based crime prevention.
Family-Based Prevention
Five types of family-based programs have been found to be effective in preventing crime:
Home visitation; Day care/preschool; Parent training (with younger children); Home/community parent training (with older children); Multisystemic therapy.
Community-Based Prevention
Three types of community-based programs are considered to be promising in preventing crime:
Gang member intervention programs that are focused on reducing cohesion among youth gangs and individual gang members;
Community-based mentoring; After-school recreation.
School-Based Prevention
Three types of school-based programs have been found to be effective in preventing crime:
School and discipline management; Interventions to establish norms or expectations for behavior; Self-control of social competency instruction using cognitive-behavioral instruction
methods.
Placed-Focused Prevention
Three types of place-focused programs have been found to be effective in preventing crime:
Nuisance abatement; Closed-circuit television surveillance cameras; Improved street lighting.
3
Appendix: Excerpt from Evidence-Based Crime Prevention*
* Welsh, Brandon C., Evidence-Based Crime Prevention: Scientific Basis, Trends, Results and Implications for Canada, Research Report 2007-1, Ottawa, Ontario, Canada: National Crime Prevention Centre, Public Safety Canada, June 2007, available at http://www.publicsafety.gc.ca/prg/cp/_fl/evidenced-based-cp-e.pdf.
Sparrow—One Week in Heron City (Case B) | 33
Author Note: MalcolmK.SparrowisprofessorofthePracticeofPublicManagementattheJohnF.Kennedy
SchoolofGovernmentatHarvardUniversity.ThiscasestudywaswritteninsupportoftheExecutiveSession
onPolicingandPublicSafetyattheHarvardKennedySchoolofGovernment.Itisdesignedtoserveasabasis
fordiscussionsregardingthenatureofanalyticsupportformodernpolicing.Theauthoracknowledgesvalu-
ableresearchassistanceprovidedbyBaillieAaron,withrespecttopolicingstrategies,andbyDr.LibbyJewett,
HypoxiaResearchProgramManagerattheNationalOceanographicandAtmosphericAdministration,with
respect to marine biology.
U.S. Department of JusticeOffice of Justice ProgramsNational Institute of Justice
Washington, DC 20531Official BusinessPenalty for Private Use $300
presorted standardpostage & fees paid
doJ/niJpermit no. g –91
*NCJ~227665*
NCJ 227665
Members of the Executive Session on Policing and Public Safety
Colonel Rick Fuentes, Superintendent, New Jersey State Police
Chief George Gascón, San Francisco Police Department
Mr. Gil Kerlikowske, Director, Office of National Drug Control Policy
Chief Cathy Lanier, Washington D.C. Metropolitan Police Department
Ms. Adrian Nicole LeBlanc, Visiting Scholar, New York University
Professor Tracey Meares, Walton Hale Hamilton Professor of Law, Yale Law School
Chief Constable Peter Neyroud, Chief Executive, National Policing Improvement Agency (UK)
Christine Nixon, Chair, Victorian Bushfire Reconstruction & Recovery Authority (Australia)
Chief Richard Pennington, Atlanta Police Department
Mayor Jerry Sanders, City of San Diego
Professor David Sklansky, Professor of Law, Faculty Co-Chair of the Berkeley Center for Criminal Justice, University of California, Berkeley, School of Law
Mr. Sean Smoot, Director and Chief Legal Counsel, Police Benevolent & Protective Association of Illinois
Professor Malcolm Sparrow, Professor of Practice of Public Management, Kennedy School of Government, Harvard University
Chief Darrel Stephens, Charlotte-Mecklenburg Police Department (retired)
Professor Christopher Stone, Guggenheim Professor of the Practice of Criminal Justice, Kennedy School of Government, Harvard University
Mr. Jeremy Travis, President, John Jay College of Criminal Justice
Mr. Rick VanHouten, President, Fort Worth Police Association
Professor David Weisburd, Walter E. Meyer Professor of Law and Criminal Justice, Director, Institute of Criminology, Faculty of Law, The Hebrew University and Distinguished Professor, Department of Administration of Justice, George Mason University
Dr. Chuck Wexler, Executive Director, Police Executive Research Forum
Chief Anthony Batts, Oakland Police Department
Professor David Bayley, Distinguished Professor, School of Criminal Justice, State University of New York at Albany
Dr. Anthony Braga, Senior Research Associate, Lecturer in Public Policy, Program in Criminal Justice Policy and Management, Kennedy School of Government, Harvard University
Chief William J. Bratton, Los Angeles Police Department
Chief Ella Bully-Cummings, Detroit Police Department (retired)
Ms. Christine Cole (Facilitator), Executive Director, Program in Criminal Justice Policy and Management, Kennedy School of Government, Harvard University
Commissioner Edward Davis, Boston Police Department
Chief Ronald Davis, East Palo Alto Police Department
Chief Edward Flynn, Milwaukee Police Department
Learn more about the Executive Session at: NIJ’s Web site: http://www.ojp.usdoj.gov/nij/topics/law-enforcement/executive-sessions/welcome.htm
Harvard’s Web site: http://www.hks.harvard.edu/criminaljustice/executive_sessions/policing.htm