A comparison of prospective and retrospective diary methods of assessing alcohol use among university undergraduates.

The objective of this study is to compare data about the quantity of alcohol consumed by university undergraduates using a prospective diary with those data collected using a retrospective diary. Five hundred and ninety-eight subjects were randomly selected and divided into two groups matched for age, sex, year of study and subject group; one group received a prospective and one a retrospective questionnaire-301 students received prospective and 297 retrospective questionnaires. Sixty-eight per cent responded to the prospective and 75 per cent to the retrospective survey. There was no significant difference in the median alcohol consumption detected for men or women in this study (p = 0.13; p = 0.47). However, the prospective diary recorded a greater proportion of heavy drinkers, this difference being significant for men and women (p less than 0.05). The quantitative results of the retrospective diary are similar to those obtained by a similar method in a previous survey. The conclusion is that a prospective diary detects a greater proportion of heavy drinkers than a retrospective diary. The prospective survey may be the most appropriate method for assessing alcohol use in certain situations.