Using category midpoints (or values noted), the same variables were computed as in the NDSHS, viz, maximum, capped volume, number of drinking days, and respective capped or prorated frequencies of the GF ranges.
Considering first the Australian 2004 NDSHS, Table 1 gives results of analyses using the distributions of the yesterday amounts, in standard drinks for corresponding GF quantity ranges.
Unlike the NAS GF measure, which for efficiency begins with a maximum question, allowing unnecessary GF quantity levels to be skipped, the paper-and-pencil format used in the Australian NDSHS requires derivation of the maximum based on the pattern of completion of the GF matrix.
Table 4 results were very similar to those found for the NDSHS (see Table 1), although the upper levels of the NAS GF quantity ranges (13g US standard drinks) differ from those used in the Australian survey (10g standard drinks).
In both cases we consider 1-2 drink levels combined (the NDSHS and standard NAS format) combining distinct 1 drink and 2 drink levels in the US 12-month GF.
Thus, as with the NDSHS, for the US sample requiring adjustment, the mean volume in drinks per day given by the capping procedure is closer to the diary-based mean volume than the equivalent result based on prorating.
The self-report measurement study permits an analysis not possible in the case of the NDSHS yesterday measure since 28 days diary data provides a distribution across drinking quantity levels to compare with the 12-Month GF levels on an individual (not only a group) basis.
We wish to thank Jinhui Zhao for drink ethanol calculations for the Australian NDSHS.