Table 2. Differences in Prevalence Rates and Means in Alcohol Involvement Variables Between Washington State and Victoria.

		Washington		Victoria
		Prevalence		Prevalence
Variables	Range	(%)*	Mean (SD)	(%)*	Mean (SD)	Effect size d
Early onset of alcohol use	0∼4	43.7	1.23 (1.57)	65.9	1.86 (1.58)	.40
Frequent alcohol use	0∼3	21.5	0.30 (0.66)	43.6	0.68 (0.92)	.47
Heavy drinking	0∼3	15.4	0.28 (0.74)	29.9	0.53 (0.92)	.30
Alcohol harm	0∼6	20.8	0.53 (1.24)	35.9	0.98 (1.66)	.31

Note: All of the mean differences between states were significant using t-tests at p < .001: mean and pooled standard deviations were used to calculate effect size, d specified by Cohen (1988) that d of.20 indicates small, of .50 indicates medium, and of .80 indicates large effect size.

^*Prevalence rates were computed based on the proportion of youth involved in the indicated alcohol problems; for early onset of alcohol use, prevalence was estimated based on the number of youth who had initiated alcohol by age 13.