bottom up approach Flashcards
who developed the bottom up approach
Canter
what did canter propose regarding offender profiling
- proposed profiling can and should be based on psychological theory + research
define the bottom up approach
data driven approach where statistical technqiues are used to produce predictions about likely characteristics of offender
what are the 3 main features of the bottom up approach
- interpersonal coherence
- forensic awareness
- small space analysis
outline what interpersonal coherence is as feature of bottom up approach
- people tend to be consistent in their behaviour - how they behave at scene is how they may behave elsewhere
outline forensic awareness as a feature of bottom up approach
- certain behaviours reveal awareness of particular police techniques + from past experiences
- individuals arrested before found to conceal more due to previous knowledge of criminal system
outline small space analysis as feature of bottom up approach
- data from crime scenes + offender characteristics are correlated so most common connections can be identified
- trying to predict future data
who developed small space analysis
Canter
supporting evidence for small space analysis being main feature of bottom up approach
- salfati + canter analysed co occurrence of 48 crime scenes + offender characteristics which were taken from 82 murder cases were victim was stranger
- they found 3 themes
what were the 3 themes identified when Salfati and Canter analysed co occurance of crime scenes
- instrumental opportunistic (instrumental - accomplishing a goal, opportunistic - offender took easiest opportunities)
- instrumental cognitive (concern abt being detected - more planning)
expressive impulsive (uncontrolled offence - heat of moment, may feel provoked by victim)
define geographical profiling
analyses location of series of crime scenes and considers how they may relate to offenders place of residence
how did Canter help towards geographical profiling
he proposed people do not just reveal themselves through the crimes they commit but through locations they choose
- location of crime can be clue in investigation
who proposed circle theory
canter and larkin
outline circle theory
Canter and Larkin proposed most offenders have spatial mindset when committing crime (commit them in imagined circle)
- criminals base would be in centre of circle
- identified two forms of offenders (marauders and commuters)
what is a marauder - circle theory
offender commits crime within same geographical areas their residence
what is a commuter - circle theory
offender travels to another geographical area and commits crime within defined space
who developed criminal geographical targeting
rossmo
define what criminal geographical targeting is
- computerised system based on Rossmo’s formula which produces 3 dimensional maps (Jeopardy surface)
what is a jeopardy surface (what do the colours on it indicate)
map used in criminal geographical targeting - different colours indicate likely closeness of residence
what does a Jeopardy surface display
displays data relating to time, distance and movement of offender too and from crime scene
evaluation points for bottom up approach to offender profiling
scientific basis BUT biased (-)
usefulness (+)
circle theory lack of success (-)
dangers of profiling (-)
expand on eval point - scientific basis BUT biased (-)
- bottom up approach considered to be more scientific than top down approach due to use of objective statistical techniques and computer analysis
- BUT issues occured with approach - data used to drive system is only related to offenders who have been caught (tell little about patterns of behaviour related to unsolved crimes)
- using computer programmes - someone has to develop formula used and may be incorrect (vulnerable to human error)
- means bottom up approach has potential to be objective and systematic however when used it can be biassed.
expand on eval point - usefulness (+)
- Canter’s first attempt at profiling led to police interested in method used
research supports usefulness - Copson surveyed 48 police forces, found 75% of police officers said profiler advice was useful and would use profiler again
- suggested method may not be useful in identifying actual offender but benefits outweigh
- profiling been proven useful for some
expand on eval point - circle theory lack of success (-)
- Canter and Larkin studied 45 sexual assaults, showed support for model by distinguishing whether they were marauders or commuters
- 91% offenders were marauders - classification doesnt seem useful as almost all offenders are marauders
- Petherick pointed out number of flaws in model : if persons home base is not actually centre of circle it means police may lookin in wrong place
- limiting approach and its effectiveness because there are critics going against theory (lacks validity)
expand on eval point - dangers of profiling (-)
- although profiling is useful in helping police narrow down field of possibilities - sticking to closely with one profiler can cause mistakes down to human error
- example : case of Nickell who was stabbed in Wimbledon, forensic psychologist Paul Britton helped police to create profile which led to identification of Colin Stagg which later turned out actual murderer was Robert Napper who had been ruled out due to his height not matching picture
- using bottom up approach is can limit findings due to decisions being made too soon all down to human error
- limiting the validity
