title: The Effect of Perceived Risk on the Combined Used of Alcohol and Marijuana: Results from Daily Surveys.
abstract: BACKGROUND
  Studies looking at the association between perceived risk and simultaneous use of alcohol and marijuana are scarce. The present study has three purposes: (1) To examine the association between alcohol and marijuana use at the daily level; (2) To document how this association varies by the perceived risk of using alcohol and marijuana simultaneously; (3) To test whether the association varies by college attendance.
  
  
  METHODS
  89 young adults (Mean Age = 18.3 years,SD= 0.5) participated between October 2012 and May 2013. Participants completed a 30-minute survey followed by 14 brief daily surveys in each of three waves.
  
  
  RESULTS
  Alcohol use on a given day was associated with increased odds of marijuana use that day, especially among young adults with lower perceived risk. For college students, the association between alcohol and marijuana was weaker than for non-students.
  
  
  CONCLUSIONS
  Alcohol and marijuana use were associated at a daily level, especially among young adults with lower perceived risk and those who were not attending college.
authors.affiliation: Department of Educational Studies, College of Education and Human Ecology, The Ohio State University, 29 W. Woodruff, Room 314 Ramseyer Hall, Columbus OH 43210-1116.
authors.forename: Gloria
authors.initials: G
authors.lastname: Yeomans-Maldonado
authors.affiliation: Institute for Social Research, University of Michigan, 426 Thompson Street, Ann Arbor, MI 48106-1248.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Patrick
keywords: Marijuana use; alcohol use; daily; perceived risk; young adults