"420 Friendly": Revealing Marijuana Use via Craigslist Rental Ads

TL;DR

This study develops a text-mining approach to analyze Craigslist rental ads for marijuana use concerns, providing a new public health surveillance tool that correlates online data with legal marijuana use across U.S. states.

Contribution

The paper introduces a novel method for extracting marijuana-related concerns from Craigslist ads and links this data to geographic and legal contexts for public health monitoring.

Findings

Strong correlation between Craigslist ads and Google searches in legal states

Detection of marijuana use concerns in states where use is illegal

Method can inform public health policy and regulation development

Abstract

Recent studies have shown that information mined from Craigslist can be used for informing public health policy or monitoring risk behavior. This paper presents a text-mining method for conducting public health surveillance of marijuana use concerns in the U.S. using online classified ads in Craigslist. We collected more than 200 thousands of rental ads in the housing categories in Craigslist and devised text-mining methods for efficiently and accurately extract rental ads associated with concerns about the uses of marijuana in different states across the U.S. We linked the extracted ads to their geographic locations and computed summary statistics of the ads having marijuana use concerns. Our data is then compared with the State Marijuana Laws Map published by the U.S. government and marijuana related keywords search in Google to verify our collected data with respect to the demographics of marijuana use concerns. Our data not only indicates strong correlations between Craigslist ads, Google search and the State Marijuana Laws Map in states where marijuana uses are legal, but also reveals some hidden world of marijuana use concerns in other states where marijuana use is illegal. Our approach can be utilized as a marijuana surveillance tool for policy makers to develop public health policy and regulations.