Assessing Risk for Violence

Stephen D. HartSimon Fraser University

Violence

Actual, attempted, or threatened physical harm that is deliberate and nonconsenting Includes violence against victims who

cannot give full, informed consent Includes fear-inducing behavior, where

threats may be implicit or directed at third parties

Violence as a Choice

The proximal cause of violence is a decision to act violently

The decision is influenced by a host of biological, psychological, and social factors Neurological insult, hormonal abnormality Psychosis, personality disorder Exposure to violent models, attitudes that

condone violence

We Can’t Predict Violence…

Violence is too rare to predict with any accuracy, by any means

“Professional” decisions are particularly bad

Predictions of violence necessitate a deterministic view of behavior

Or, Can We?

The issue of prediction is moot Don’t predict, evaluate risk (e.g., suicide)

Regardless, predictions made by professionals are reliably better than chance

The scientific literature on violence is large and growing

Any choice can be predicted

What is Risk Assessment?

Process of understanding a hazard to limit its potential negative impact Hazard identification (which events

occur?)

Hazard accounting (how frequently?) Scenarios of exposure (under which

conditions?)

Risk characterization (conditions present?) Risk management (which interventions?)

Nature of Violence Risk

Violence risk is a multi-faceted construct Nature: what kinds of violence might occur? Severity: how serious might the violence be? Frequency: how often might violence occur? Imminence: how soon might violence occur? Likelihood: what is the probability that violence

might occur?

Risk is Context-Specific

We never know a person’s risk for violence; we merely estimate it assuming certain conditions Assuming institutionalization, assuming

release with supervision, assuming release without treatment for substance use…

Consequently, relative or conditional risk judgments are more useful than absolute or probabilistic risk judgments

Goals of Risk Assessment

To make better decisions Improve consistency Protect public safety Guide intervention

Protect clients’ rightsLiability management

Risk Characterization

Content Issues

What to Include?

Three primary criteria Empirical (predictive accuracy) Professional (practical utility) Legal (fairness and reasonableness)

Problems With Empirical Criterion

Not everything that is important has been proven or validated scientifically Can lead to exclusion of “good” but rare

or difficult-to-assess risk factorsPrediction cause, explanation, or

intervention Can lead to inclusion of “bad” but

common or easy-to-assess factors

Example: The SIEVE

Age Young is badSex Male is badFacial hair Dense is badFoot sizeBig is bad

Problems With Professional Criterion

Focus on dynamic factors may bias risk assessments Can lead to exclusion of “good” but

static or easy-to-ignore factorsConventional wisdom of

professionals may be plain wrong Can lead to inclusion of “bad” but vivid

or dramatic factors

Example: Clinical Intuition

Depression Present is goodAnxiety Present is goodIntelligence High is goodRorschach Seeing viscera is bad

Problems With Legal Criterion

Useful for excluding risk factors, but not for including them

It can be argued that almost any risk factor is unfair or unreasonable in some respect

Risk Characterization

Procedural Issues

Conventional Approaches

Professional judgment Unstructured or “clinical” Anamnestic (see Melton et al., 1997) Structured (e.g., HCR-20, SVR-20)

Actuarial decision-making Psychological tests (e.g., MMPI-2, PCL-R) Risk scales (e.g., VRAG, RRASOR)

Professional Judgment

Most commonly-used method for violence risk assessment Familiar to professionals Familiar to courts and tribunals

General strengths of method Flexible (easy administration) Requires limited training and technology Person-centered (“idiographic”)

Unstructured: Features

No constraints on evaluation Any information can be considered Information can be gathered in any

mannerNo constraints on decisions

Information can be weighted and combined in any manner

Results can be communicated in any manner

Unstructured: Limitations

No systematic empirical support Low agreement (unreliable) Low accuracy (unvalidated) Foundation is unclear (unimpeachable)

Relies on charismatic authorityDecisions are broad bandwidthFocus is on culpability, not action

Anamnestic: Features

Imposes minor structure on evaluation Must consider, at a minimum, nature and

context of past violenceAction-oriented

Logically related to development of risk management strategies

Consistent with “relapse prevention” or “harm reduction” approaches

Anamnestic: Limitations

Unknown reliabilityUnknown validityAssumes that history will repeat

itself Violent careers are static Violent people are specialists

Structured: Features

Imposes major structure on evaluation Must consider, at a minimum, a fixed and

explicit set of risk factors Specifies process for information-gathering

Imposes minor structure on decision Specifies language for communicating

findingsAction-oriented

Structured: Limitations

Requires “retooling” of evaluation process Systematized information-gathering New training and technology

Justification for imposing structure requires inductive logic (faith) What works elsewhere will work here Professional discretion is appropriate

HCR-20

HCR-20, version 2 Webster, Douglas, Eaves, & Hart (1997) Designed to assess risk for violence in

those with mental or personality disorders

10 Historical, 5 Clinical, and 5 Risk Management factors

Applications

Assess clinical evaluations of violence risk across a broad range of populations and settings Civil and forensic psychiatric, correctional Institution, community

Monitor clinical and situational factors that may be relevant to violence

Guide risk management strategies

Conceptual Basis

Intended to bridge clinical and empirical domains and knowledge bases Evidence-based risk assessment

Content determined rationally Based on reviews of scientific and

professional literatures Not optimized on a particular sample

Temporal Organization

P as t (S ta tic )D ocu m en ted

(1 0 Item s)

H is to rica l

P resen t (D yn am ic )O b served(5 Item s )

C lin ica l

F u tu re (S p ecu la tive )P ro jec ted(5 Item s )

R isk M an ag em en t

V io len ce R isk

Historical Factors

Previous violenceYoung age at first

violenceRelationship

instabilityEmployment

problemsSubstance use

problems

Major mental illness

PsychopathyEarly

maladjustmentPersonality

disorderPrior supervision

failure

Clinical & Risk Management Factors

Lack of insightNegative attitudesActive symptoms

of major mental illness

ImpulsivityUnresponsive to

treatment

Plans lack feasibilityExposure to

destabilizersLack of personal

supportNoncompliance with

remediation attempts

Stress

Actuarial Decision-Making

Commonly-used adjunctive method for violence risk assessment Familiar to some professionals

(psychologists) Somewhat familiar to courts and tribunals

General strengths of method Highly structured/systematic (“objective”) Empirically-based (“scientific”)

Psychological Tests: Features

Measure some disposition that predicts violence, according to past research

Reliability and validity of test-based decisions has been evaluated

Imposes major structure On some part of the evaluation process On some part of the decision-making

process

Psychological Tests: Limitations

Require professional judgment Which tests to use How to interpret scores

Justification of use requires inductive logic Our population is like theirs Our use of the test is like theirs

PCL:SV

Symptom construct rating scale requires clinical / expert judgment based on “all data”

Data obtained from two primary sources: review of case history (required) interview / observation

(recommended)

PCL:SV: Items

Part 1SuperficialGrandioseDeceitfulLacks remorseLacks empathyDoesn’t accept

responsibility

Part 2 ImpulsivePoor behavioral controlsLacks goals IrresponsibleAdolescent antisocial

behaviorAdult antisocial

behavior

PCL: Summary #1

The correlation between the PCL and violent recidivism averages about .35 Regardless of length of follow-up Even in sex offenders, forensic patients,

women, delinquents — even in nonviolent, nonpsychopathic offenders

Association is quasi-linear (positive and monotonic)

PCL: Summary #2

Among psychopaths (e.g., PCL-R > 30) released from prison, the 5-year violent reoffense rate is about 70% Versus about 30% in low group (< 20)

and 50% in medium group (21-29) Versus low group, psychopaths are at

very high risk for reoffense (rate ratio = 2x to 3x; odds ratio = 5x to 10x)

PCL: Summary #3

Psychopaths not only commit more violence, they commit different kinds of violence

The violence of psychopaths often has unusual or atypical motivations Instrumentality/gain Impulsivity/opportunism Sadism

PCL: Conclusions

Psychopathy must be assessed as part of comprehensive violence risk assessments

The presence of psychopathy compels a conclusion of high risk

The absence of psychopathy does not compel a conclusion of low risk

Psychopathy must be assessed by trained professionals using adequate procedures

Decision Tree

Homicidal/suicidal?

NO

YES High Risk

Psychopathic?(e.g., PCL-R > 30)

NO

High Risk

Assess other factors(e.g., HCR-20)

Sexual sadism?

NO

High RiskYES

YES

Risk Scales: Features

Designed solely to predict an outcome

High-fidelity Optimized for specific outcome, time

period, population, and contextImpose rigid structure

On all of the evaluation process On all of the decision-making process

Risk Scales: Limitations

Still require professional judgment Which scales to use How to interpret scores

Justification of use still requires induction Our population is like theirs Our use of the test is like theirs

Results may be easily misinterpreted Pseudo-objective, pseudo-scientific

VRAG

Violence Risk Appraisal Guide Quinsey et al. (1998) Constructed in adult male patients

assessed or treated at a maximum security hospital

12 items weighted according to ability to postdict violence over 7 year follow-up

Total scores divided into 9 bins, with estimated p(violence) from 0% to 100%

VRAG Items

PCL-R scoreElem. school

problemsPersonality disorderAge (—)Separated from

parents under age 16Failure on prior

conditional release

Nonviolent offense history

Never marriedSchizophrenia (—)Victim injury (—)Alcohol abuseFemale victim (—)

VRAG: Potential Problems

The VRAG is, in essence, a history lesson:

What if patient profile changes?What if p (violence) changes?What if the assessment context

changes?

VRAG: Actual Problems?

Paul Bernardo is a convicted serial murderer (3 sexual homicides) and serial rapist (75 known rapes)

Currently serving life imprisonment for murder, and an indeterminate sentence for the rapes

VRAG completed on the basis of case history data

Bernardo’s VRAG Results

PCL-R score +4 Elem. school… -1 Personality disorder +3 Age 0 Separated from… -2 Failure on prior… 0 Nonviolent offense… -2 Marital status -2 Schizophrenia +1 Victim injury -2 Alcohol abuse +1 Female victim -1

Total: -1

Bin #: 4

p(viol): 17% - 31%

Problems With All

Focus on negative characteristics “Sticky” labels What about strengths (resources,

“buffer” factors)? Risk assessment risk management

What to do with high-risk individuals?Quality control

Who will assess risk, and how?

Risk References

Boer, D. P., Hart, S. D., Kropp, P. R., & Webster, C. D. (1997). Manual for the Sexual Violence Risk-20: Professional guidelines for assessing risk of sexual violence. Burnaby, British Columbia: Simon Fraser University.

Grove, W. M., & Meehl, P. E. (1996). Comparative efficiency of informal (subjective, impressionistic) and formal (mechanical, algorithmic) prediction procedures: The clinical-statistical controversy. Psychology, Public Policy, and Law, 2, 293-323.

Kropp, P. R., Hart, S. D., Webster, C.W., & Eaves, D. (1995). Manual for the Spousal Assault Risk Assessment Guide, 2nd ed. Vancouver, BC: British Columbia Institute on Family Violence.

Meehl, P. E. (1996). Clinical versus statistical prediction: A theoretical analysis and a review of the literature. Northvale, NJ: Jason Aronson. (Original work published in 1954.)

Risk References (cont.)

Melton, G. B., Petrila, J., Poythress, N. G., & Slobogin, C. (1997). Psychological evaluations for the courts: A handbook for mental health professionals and lawyers (2nd ed.). New York: Guilford.

Quinsey, V. L., Rice, M. E., Harris, G. T., & Cormier, C. (1998). Violent offenders: Appraising and managing risk. Washington, DC: American Psychological Association.

Webster, C. D., Douglas, K. S., Eaves, D., & Hart, S. D. (1997). HCR-20: Assessing risk for violence, version 2. Burnaby, British Columbia: Simon Fraser University.

But How Accurate Are

Characterizations of Risk?

A Complex Phenomenon

Studying the accuracy of risk characterizations is difficult due to the complexity of… The characterizations The violence The follow-up Indexes of accuracy

The Characterizations

Evaluator: Professional vs. researcher; novice versus expert

Process: Clinical vs. actuarial, contextual vs. context-free

Timing: Admission vs. discharge, static vs. dynamic

Metric: Uni- vs. multi-dimensional, categorical vs. continuous

The Violence

Direction: Self vs. others, acquaintances vs. strangers

Nature: Instrumental vs. reactiveSeverity: Threats vs. battery vs.

homicideFrequency: Single vs. multiple eventsContext: Situational precipitants or co-

factors

The Follow-Up

Data source: Patient vs. collaterals vs. records

Time at risk: Weeks vs. months vs. years

Interventions: Dynamic factors, life events

Monitoring: Continuous vs. endpoint

Indexes of Accuracy

Comparison group: Other patients vs. normals

Statistic: Uni- vs. multi-variate, timeWeighting of errors: Equal vs.

differential Interpretation: Chance vs. status quo

vs. perfection

OutcomePrediction Not Violent Violent

Low Risk High Risk

Science Responds to Complexity

Example: Psychopathy

OutcomePrediction Not Violent Violent

Low Risk(Non-psychopath)

90 24

High Risk(Psychopath)

12 40

Harris, Rice, & Cormier (1991)

Example (cont.)

In this study... Accuracy of positive predictions is 77% Accuracy of negative predictions is 79% Overall accuracy is 78% Chance-corrected agreement is 53% Correlation is .53 Odds ratio is 12.5

Example (cont.)

So, how did we do? Relative to chance: Great! Relative to perfection: Awful! Relative to the status quo: ???

What is the status quo?

Predictions of violence using the PCL-R typically have an effect size (r) of about .35; the average effect size for psychosis is about .30

An effect size of .40 may be the “forensic sound barrier”

But what is the status quo in other human endeavors?

Meta-Meta-Analysis

Lipsey & Wilson (1993) reviewed 302 meta-analyses

Determined typical effect sizes for psychological, educational, and medical interventions

Psychological Interventions

CBT — depression .44Psychotherapy — any .39Correctional programs (youths) .23

— any Diversion (youths) — recidivism.20Correctional treatment (adults) .12

— any

Educational Interventions

Small classes — class climate .26Tutoring — grades .20Small classes — grades .10Media campaigns — seatbelt use

.06

Medical Interventions

Speech therapy — stuttering .54Bypass surgery — angina pain .37Cyclosporine — organ rejection.15Bypass surgery — mortality .07ASA — heart attack .04

Violence Predictions in Context

Speech therapy — stuttering .54CBT — depression .44Bypass surgery — angina pain .37Psychopathy — violence .35Psychosis — violence .30Small classes — class climate .26

Conclusions

Violence predictions, on the whole, are just as good as most other human prognostications

Consider other fields... Stock analysts Meteorologists Fire inspectors Structural engineers

Risk Assessment:

Reports and Testimony

General Issues

Acknowledge professional qualifications But, less important than approach used

Acknowledge limits of information base But, comprehensiveness depends on context

Explain risk factors considered Empirical, professional, legal justification

Acknowledge uncertainty of “predictions”

Do Don’t

Use multiple approaches

Make relative or conditional risk judgments

Make detailed risk management recommendations

Rely on a single approach

Make absolute or probabilistic risk judgments

Ignore the issue of what can or should be done

Special Issues: Professional

Report should tell a story Summarize the circumstances of past

violence and any recent changes in them Describe the likely nature and context

(scenarios) of future violence Identify factors that may increase risk and

therefore serve as flags for re-assessment Recommend, evaluate, and prioritize risk

management strategies

Cross-Exam: Professional

What, if any, is the basis of your expertise in the assessment of violence risk?

What is the scientific basis for your decision (not) to follow these procedures?

What is the scientific basis for your decision (not) to consider these factors?

Can you state with any reasonable degree of scientific certainty the likelihood that X will be violent?

Special Issues: Actuarial

Report should provide full interpretation of test scores Be familiar with research supporting the

test’s reliability and validity Discuss general limitations of the test Discuss limitations of the test in this

case

Cross-Exam: Actuarial

Isn’t it arbitrary to consider risk factors such as A, B, and C, but to ignore D, E, and F?

Is there any scientific evidence that scale Z predicts outcome Y in patients at this clinic?

How do you know that predictions using scale Z are accurate for Mr. X?

By using scale Z, aren’t you simply relying on statistical profile evidence?

Contact Information

Stephen D. Hart, Ph.D.Department of PsychologySimon Fraser UniversityBurnaby, British ColumbiaCanada V5A 1S6Tel: 604.291.5485 / Fax: 604.291.3427E-mail: shart@arts.sfu.caURL: www.sfu.ca/psychology/groups/faculty/hart