It should be noted that the greater proportion of non-users relative to users, who scored a ‘0’ across all items may have contributed to the high estimates of internal consistency for cigarette use and alcohol use. Questions that assessed ‘ever use’ revealed that 60.5% of respondents had never smoked at Time 1 and 64.7% had not had an alcoholic drink (not just a taste). Alcohol use and cigarette use at Time 1 and Time 2 were positively skewed and kurtotic. The non-normal distributions of the measures of cigarette use and alcohol use were addressed using a logarithmic transformation that produced a reduction in both the skew and kurtosis value. Before transforming the variables, the skewness values ranged from 1.66 to 4.37. The kurtosis values ranged from 3.07 to 23.22. After transforming the data the skewness values ranged from 0.70 to 3.00 and the kurtosis ranged from 0.69 to 9.72. Although cigarette use (Time 1, 2) still had a comparatively high skew and kurtosis value, the sample size of 2538 suggested that the deviation would be unlikely to make a substantive difference to the pattern of results (Tabachnik & Fidell, 2001).
