Other limitations are these. Because we focused on the transitional first year of college, this study does not provide information about risk for other groups. Risk processes likely vary across groups. For example, we consider it likely that negative urgency, rather than positive urgency, predicts problem drinking among individuals in other life circumstances. In addition, this prospective investigation relied on questionnaire self-report measures. Although measures of the traits have been shown to be consistent across method of assessment [20, 21], it may be that interviews would have provided more accurate estimates of drinking behavior. Our retention rate of 70% is another limitation. Although the missing data appear to have been missing at random, and although the EM data imputation technique appears to present unbiased estimates of population parameters, one cannot know with certainty whether the loss of data altered the findings. Finally, the sample was predominantly Caucasian and female and included only U.S. first year college students enrolled in an Introduction to Psychology course. It is thus not clear to whom, beyond the college student population, these results generalize. Further
