How many versus how much: 52 weeks of alcohol consumption in emerging adults

In previous research using timeline follow-back methods to closely monitor drinking and related variables over the first year of college (9 months), we showed that drinking varied considerably over time in accord with academic requirements and holidays. In a new community sample (N = 576) of emerging adults (18- and 19-year-olds who reported having begun drinking prior to recruitment), we used similar methods to compare drinking patterns in college and noncollege individuals over a full calendar year (including summer). To reduce the extreme distortion in computations of average drinking over restricted time spans (i.e., 1 week) that arise because large numbers of even regular drinkers may not consume any alcohol, we analyzed data using recently developed two-part latent growth curve modeling. This modeling distinguished consumption levels from numbers of individuals drinking in a given period. Results showed that drinking levels and patterns generally did not differ between college and noncollege drinkers, and that both groups responded similarly to even those contexts that may have seemed unique to one (i.e., spring break). We also showed that computation of drinking amounts without accounting for "zero drinkers" could seriously distort estimates of mean drinking on some occasions; for example, mean consumption in the total sample appeared to increase on Thanksgiving, whereas actual average consumption for those who were drinking diminished.