Appendix A: Recommended changes to conversion factors in HSE

The revised consumption estimates are restricted to beer, cider and wine only, they do not address relative consumption levels of different types of drink.

Currently, the HSE asks participants about their consumption of beers, cider and wine in two ways: first, the amount drunk on the day they drank the most in the last week, and then about their usual consumption in the last 12 months.

For all survey participants who have drunk alcohol at all in the last 12 months, the interview asks about consumption of different types of drinks, using an introductory question in this format:

• How often have you had a drink of [type of drink] during the last 12 months?

Different types of beer and cider were asked about in two categories:

• I'd like to ask you first about normal strength beer, lager, stout, cider or shandy which has less than 6% alcohol. How often have you had a drink of normal strength beer, lager, stout, cider or shandy (excluding cans and bottles of shandy) during the last 12 months?
• Now I'd like to ask you about STRONG BEER OR CIDER which has 6% or more alcohol (e.g. Tennant’s Extra, Special Brew, Diamond White). How often have you had a drink of strong BEER, LAGER, STOUT or CIDER during the last 12 months?

From 2022, beer and cider have been asked about separately, although the same format is used to separate it into normal strength and strong categories.

Wine was asked about in a single question:

• How often have you had a drink of wine, including sparkling wines such as champagne or prosecco, during the last 12 months?

If asked, interviewers can provide additional detail about the types of drinks covered by these questions.

Follow-up questions record the frequency of drinking each type of drink and the amount usually drunk on days when they were drunk. For beers and ciders these amounts can be recorded in pints, small cans, large cans or bottles. For wine these amounts can be recorded in bottles and glasses (with glasses separated into small/125ml, standard/175ml and large/250ml).

These questions are asked by the interviewer for most adults; those aged between 16 and 24 are asked the same questions in a self-completion format. The questions used are documented in the HSE 2019: Questionnaires, field documents and measurement protocols. See page 80 onwards for questions asked of adults.

Since 2006, reported consumption of beer and cider was converted into alcoholic units using the following equivalents

Table 1A: How HSE converts reported consumption of beers and ciders into units of alcohol

The conversion factors applied do not imply consistent ABV. Estimates for bottles and cans are approximations.

Table A2: Approximate ABVs implied by HSE conversion factors

The HSE Alcohol Working Group identified two changes that might improve the quality of estimates:

• to separate and update the estimates for large cans and bottles, given that the range for the latter is wider, and
• to increase the conversion factor for normal strength beers in pints, large cans, or bottles

Table A3: Proposed revised conversion factors for beers and ciders

These changes would reflect an ABV of 4.1% for pints of normal strength beer (compared with 3.5% using the previous factors). The range of strengths for normal strength beer in large cans would be 4.5% to 5.0% (rather than 3% to 4.5%), and for strong beer in large cans the range would be 7.0% to 8.0% (rather than 4.5% to 6.8%). A realistic estimate for bottles where the size is unknown was harder: the range of sizes for brands on sale at supermarkets is from 250mls to 660mls. Keeping the current conversion factors would produce a range of assumed ABV between 3% and 8% for normal strength beers and 4.5% to 12% for strong beers.

The revised conversion factors set out in Table A3 were used for the analysis in this report.

Since 2006, the calculation of wine consumption has assumed an ABV of 12.5%, and rounded all quantities (per glass or bottle) to the nearest 0.5 units. The effect of the rounding was an actual conversion rate equivalent to 12% or lower.

Table A4: Current (rounded) conversion factors applied to wine

A consistent assumption of an ABV of 12% without rounding would produce a marginal increase, since 175ml glasses would be counted as 2.1 units.

Assuming an ABV of 12.5% with unrounded unit equivalents would result in increased estimates across all measured quantities

The revised conversion factors set out in Table A5 were used for the analysis in this report.