Prioritizing Alcohol and Drug Abuse Prevention Efforts Using Spatial Analysis

This project used spatial analysis to identify areas throughout Los Angeles (LA) County where there are high concentrations of factors known to be associated with adolescent substance use.  Predictors of adolescent substance use include delinquency, school problems, abuse/neglect, availability of alcohol and marijuana, prevalence of drug and alcohol abuse in the community, and crime. Cross-sectional, de-identified address data from multiple LA County agencies were combined to create a data set of 9,244 data points of indicators known to be positively correlated with adolescent substance use. Location data included addresses of: arrests for drunk driving or alcohol/drug use offenses; juvenile probation clients; child/abuse and neglect arrests; and marijuana dispensaries. Geographic information systems (GIS) was used to geolocate addresses to create point layers, perform spatial joins of each point layer to a census tract polygon layer, and then merge point layers into one layer, using census tract ID as the unifying variable. Point density analysis created circular neighborhoods with a 1 mile radius and calculated a magnitude per unit area from point features that fall within a neighborhood around each cell. A raster image color-coded by concentration of points is produced, preventing identification of any one point used in the analysis. The Getis-Ord statistic established that clustering of risk indicators was statistically significant. This data will be compared to community assessment data on substance use prevalence among 2,837 youth ages 12-17 located throughout LA County to determine the accuracy of predicting adolescent substance use by mapping the location of risk factors.