Cannabis users were asked if they had ever experienced any of 6 DSM-IV dependence symptoms, excluding withdrawal (Waves 4 and 5) or 4 abuse symptoms (all waves). The distribution was skewed, with 12% and 14% of users endorsing only one and 2+ symptoms respectively. To avoid making normality assumptions, endorsement of any of these 10 symptoms at any assessment was dichotomously defined as problem use. Those who did not report any cannabis use were coded as missing for cannabis problems.
