The difficulties of predicting future violence Edward P. Mulvey, Ph.D. Western Psychiatric Institute and Clinic University of Pittsburgh School of Medicine Conference on Campus Violence Columbia Law School April 4, 2008

Goals Provide some background about general methods for making predictions of violence Provide some background about general methods for making predictions of violence Identify the inherent challenges to predicting campus violence Identify the inherent challenges to predicting campus violence Make some general recommendations about strategies for addressing this problem Make some general recommendations about strategies for addressing this problem

Approaches to Predicting Incidents of Violence

Actuarial Approach Same information considered for every person Same information considered for every person Consistent method for combining information Consistent method for combining information Factors considered not necessarily “causal” for that individual Factors considered not necessarily “causal” for that individual

Clinical Approach Individualized judgment Individualized judgment Range of relevant factors considered is very broad; ideally, an integrative view Range of relevant factors considered is very broad; ideally, an integrative view Operates from a theory of how violence might occur or unfold in the individual’s life Operates from a theory of how violence might occur or unfold in the individual’s life

Problems with the Actuarial Approach All the information has to be available All the information has to be available Generally assumes that all the factors apply the same to everyone Generally assumes that all the factors apply the same to everyone The risk estimate is devoid of theory The risk estimate is devoid of theory

Problems with the Clinical Approach Depends on the person doing it Depends on the person doing it Variability in: Variability in: Information gathered Information gathered Ways information is combined Ways information is combined Human biases occur Human biases occur Recency Recency Vividness Vividness Affected by organizational demands Affected by organizational demands Optimization is assumed Optimization is assumed “Satisficing” is more common “Satisficing” is more common

Actuarial vs. Clinical Prediction Old debate Old debate Suicide Suicide Job/academic success Job/academic success General findings General findings Actuarial Approach generally more accurate Actuarial Approach generally more accurate Clinical Approach more versatile Clinical Approach more versatile Issue of reliability and validity Issue of reliability and validity

Reliable, but not valid

Valid, but not reliable

Actuarial Risk Assessment Tools General violence/recidivism (mainly in mentally ill individuals) General violence/recidivism (mainly in mentally ill individuals) Historical-Clinical-Risk Management-20 (HCR-20) Historical-Clinical-Risk Management-20 (HCR-20) Violence Risk Appraisal Guide (VRAG) Violence Risk Appraisal Guide (VRAG) Classification of Violence Risk (COVR) Classification of Violence Risk (COVR) Violent Offender Risk Assessment Scale (VORAS) Violent Offender Risk Assessment Scale (VORAS) Special purpose instruments Special purpose instruments Domestic violence Domestic violence Spousal Assault Risk Assessment (SARA) Spousal Assault Risk Assessment (SARA) Risk of sex offense Risk of sex offense Static-99 Static-99 Risk of violence among juveniles Risk of violence among juveniles Early Assessment Risk List for Boys (EARL-20B) Early Assessment Risk List for Boys (EARL-20B) Manual for the Structured Assessment of Violence Risk in Youth (SAVRY) Manual for the Structured Assessment of Violence Risk in Youth (SAVRY)

Issues regarding actuarial instruments Increasingly popular because of technology Increasingly popular because of technology Optimization on chance Optimization on chance Shrinkage inevitable Shrinkage inevitable Application on particular sample might not be appropriate Application on particular sample might not be appropriate Effect of context Effect of context Information availability Information availability Outcome of decision Outcome of decision Not a replacement for clinical judgment. Integration of actuarial and clinical information is the goal Not a replacement for clinical judgment. Integration of actuarial and clinical information is the goal

Inherent Challenges to Predicting Campus Violence

Major General John Sedgwick

Problem #1: Low Base Rates Actually violent Actually violent YesNo YesNo PredictedYes Violent No , ,000 Assume that one in ten individuals is actually violent over a given time period Assume that the instrument correctly identifies 80% of the violent individuals 80% of the nonviolent individuals true positives true negatives false negatives false positives

Implications No technology will predict rare events No technology will predict rare events Secret Service study of school shootings: “There is no accurate or useful profile of the school shooter”. Secret Service study of school shootings: “There is no accurate or useful profile of the school shooter”. “profiles” may be valuable, but not because they are predictive “profiles” may be valuable, but not because they are predictive The utility of screening and assessment is not to predict for an individual, but The utility of screening and assessment is not to predict for an individual, but to identify groups with higher base rates to identify groups with higher base rates to focus prevention resources to focus prevention resources

Problem #1: Low Base Rates Problem #2: Context matters and situations change

Problem #2: Context matters and situations change Violence is usually Violence is usually dependent on proximal situational factors dependent on proximal situational factors transactional transactional Opportunities for violence Opportunities for violence may differ substantially across individuals may differ substantially across individuals can be altered by lifestyle changes can be altered by lifestyle changes presence of alcohol presence of alcohol living arrangements living arrangements

Implications Risk status may be important, but so are fluctuations in risk state Risk status may be important, but so are fluctuations in risk state Move toward management of high risk individuals and situations Move toward management of high risk individuals and situations Conditional prediction model Conditional prediction model “if….then” formulation of risk “if….then” formulation of risk Monitoring and management of “dynamic predictors” Monitoring and management of “dynamic predictors”

A research example: Substance use and violence

Study Design Select group of individuals who were highly likely to have frequent involvement in violence Select group of individuals who were highly likely to have frequent involvement in violence Weekly interviews providing daily reports Weekly interviews providing daily reports Violent incidents Violent incidents Substance use reports at daily level Substance use reports at daily level Alcohol (number of drinks) Alcohol (number of drinks) Marijuana use Marijuana use Other drugs (mostly cocaine) Other drugs (mostly cocaine) Analyses of the concurrent and lagged relationships of substance use and violence Analyses of the concurrent and lagged relationships of substance use and violence

Conditional Probability SERIOUS VIOLENCE Conditional Probability ANY VIOLENCE P (violence| alcohol only)2.3 %7.9% P (violence| marijuana only )1.6 %4.2% P (violence| other drug only)2.5 %7.4% P (violence| alcohol and mj)4.4 %10.5% P (violence| alcohol and otherdrugs)4.5 %10.2% P (violence| alcohol, mj, otherdrugs)9.0 %19.4% P (alcohol | violence)21.7 %20.2% P (marijuana | violence)32.4 %28.0% P (other drugs| violence)6.2 %5.5% P (alcohol & any drug use)9.3 % P (alcohol & any drug use| violence)23.1 %21.0% Serious violence Any violence Alcohol (> 3 drinks) Marijuana Other drugs Percent of days 1.4%3.9%8.7%20.6%2.5%

Day Before Day After Serious Violence AlcoholMarijuana Other Drugs Serious Violence Alcohol Marijuana Other Drug Odds ratios for substance use and violence one day apart for serious violence

Examples |||||||-| |---|----- Case 8 Case |------| |------| |-|------| | |--| |----|--

Testing the relation of violence and alcohol use over time

Findings Evidence for a lagged effect for alcohol use (greater than three drinks) on violence, but not the other way around Evidence for a lagged effect for alcohol use (greater than three drinks) on violence, but not the other way around No significant lagged relationships either way for marijuana use or other drugs No significant lagged relationships either way for marijuana use or other drugs Even controlling for different types of substance use, violence on one day predicts for the next day Even controlling for different types of substance use, violence on one day predicts for the next day Use of multiple substances on prior day also increases likelihood of violence Use of multiple substances on prior day also increases likelihood of violence

Problem #1: Low Base Rates Problem #2: Context matters and situations change Problem #3: Late adolescence is all about change

Problem #3: Late adolescence is all about change Late adolescence brings: Late adolescence brings: Independent social roles Independent social roles “trying on” lifestyles “trying on” lifestyles ongoing brain development ongoing brain development Different patterns of substance use Different patterns of substance use Onset period for many mental disorders Onset period for many mental disorders Substance abuse: 20 years old Substance abuse: 20 years old Mood disorders: 30 years old Mood disorders: 30 years old Schizophrenia: 20 years old (males); 30 years old (females) Schizophrenia: 20 years old (males); 30 years old (females) Involvement in violence drops off, even in serious offenders Involvement in violence drops off, even in serious offenders

Self Reported Offending Serious Adolescent Offenders - males only – average age 16 at first interview Group 4 (15.1%) Group 5 (8.5%) Group 2 (33.8%) Group 3 (18.3%) Group 1 (24.2%)

Implications Lack of solid history for use in making judgments about future violence Lack of solid history for use in making judgments about future violence Mix of developmental features and valid symptoms Mix of developmental features and valid symptoms Impulsiveness, moodiness, feelings of being picked on, feelings of rejection, tendency to blame others Impulsiveness, moodiness, feelings of being picked on, feelings of rejection, tendency to blame others Diagnostic labels are less valid Diagnostic labels are less valid Likely to confuse risk markers with risk factors Likely to confuse risk markers with risk factors Assessments have a limited shelf life Assessments have a limited shelf life

Guidelines for structuring risk assessments

1. Get the right information on the right individuals Screen using structured measures, and assess for risk when warranted Screen using structured measures, and assess for risk when warranted Use all available information consistently Use all available information consistently Use relevant assessment tools Use relevant assessment tools Group characteristics Group characteristics Target behavior of interest Target behavior of interest Use actuarial instrument as an “anchor” Use actuarial instrument as an “anchor”

Best Bets for individual assessment history of violence history of violence impulsivity (process from ideation to action) impulsivity (process from ideation to action) active ideation (mainly hostility and anger) active ideation (mainly hostility and anger) drug and alcohol use drug and alcohol use psychopathy psychopathy perceived threat perceived threat plan/access to means plan/access to means opportunities for violent encounters opportunities for violent encounters coping strategies coping strategies

2. Consider history in detail When there is past violence, assess: When there is past violence, assess: what happened what happened what factors explain the incident what factors explain the incident what factors protect against violence what factors protect against violence which risk and protective factors are currently in effect or likely to be in effect which risk and protective factors are currently in effect or likely to be in effect When there is no past violence, assess: When there is no past violence, assess: “close calls” “close calls” recent changes in life that may exceed coping capacity recent changes in life that may exceed coping capacity risk factors for violence, based on appropriate assessment protocols risk factors for violence, based on appropriate assessment protocols

3. For prevention efforts, distinguish between risk markers and risk factors Key is to focus on causal, dynamic risk factors Key is to focus on causal, dynamic risk factors Questions Questions Is this a risk factor for a particular type of violence? Is this a risk factor for a particular type of violence? Are there conditions that influence the relationship between the risk factor and violence? Are there conditions that influence the relationship between the risk factor and violence? Does the risk factor play a causal role in violence? Does the risk factor play a causal role in violence? If so, is the risk factor capable of being modified? If so, is the risk factor capable of being modified?

4. Take context and risk state seriously A single risk assessment is useless without a management plan A single risk assessment is useless without a management plan Assess individual factors and conditions periodically in high risk cases Assess individual factors and conditions periodically in high risk cases Create an environment where students trust authorities enough to share information Create an environment where students trust authorities enough to share information