Can the missing units be attributed to under-reporting?

This thesis argues that the missing units are attributable to under-reporting. A number of objections to this could be raised because there are lots of other factors at play which could explain low alcohol sales coverage, such as drinking by people outside of survey sampling frames, and consumption among visitors or tourists to the UK. Each of these competing factors that could serve as explanations for the missing units is quantified in turn in Table 2.1.

One obvious criticism of attributing the missing units wholly to under-reporting is that alcohol consumption takes place among individuals who are outside the sampling frame. This mainly concerns individuals who do not live in private households – such as people living in military or healthcare institutions - which therefore cannot be identified from the Postcode Address File.

Further, alcohol consumption has been found to be heavier among non-responders to surveys such as the GLF (see Section 2.6.2). Also, a proportion of alcohol that is taxed for sale will not actually be consumed: it will be wasted or disposed of (e.g. spillage or beer slops). Finally, the sales figures include alcohol that is consumed by foreign visitors to the UK, and that which is subsequently exported. As a result of these factors, we have several explanations for the discrepancy between self-reported consumption and alcohol sales, aside from the accuracy of

34 participants’ reporting. However, what is perhaps less obvious is that there are also several ways in which alcohol consumption is not captured in the sales data. This includes legal and illegal production and importation, informal production and homebrew, consumption of non-beverage alcohols, and consumption of UK residents while overseas.

Previous work by research teams in England and Scotland has attempted to understand and account for these differences in the data (46-48). Table 2.1 updates and extends this account relevant for this thesis. Where possible, an attempt has been made to quantify these factors, which has been particularly aided by a recent UK study by Meier and colleagues (48). Although it is not possible to quantify all the factors listed, and many of the estimates are uncertain, it is probable that the total amount of alcohol not captured in sales statistics outweighs that not captured in social surveys. It is estimated that approximately two litres of alcohol per capita is not captured in social surveys for reasons other than under-reporting, but would be taxed for sale (i.e. is included in the sales figures). Any estimate of the extent of under-reporting of alcohol consumption should take this into account when looking at the difference between consumption and sales. However, the sales data appear to under-estimate consumption, too.

This has also been noted by researchers in Sheffield and Edinburgh (47, 48). It is estimated that between 2.1 and 2.9 litres per capita is not captured in the sales data produced by HM Revenue and Customs. In this case, the synthesis of available data in Table 2.1 shows that calculating sales coverage as reported alcohol consumption as a proportion of alcohol sales, and attributing the missing units wholly to under-reporting of alcohol consumption, is actually a conservative estimate of the extent of under-reporting.

35 Table 2.1: Quantifying alcohol consumption that is not captured in social surveys, or in HMRC sales statistics

Alcohol sold but not captured in social surveys (for reasons other than under-reporting)

Alcohol consumption not captured in alcohol sales statistics

Description Estimate Description Estimate

Drinking by people outside sampling frame: under-16s

Average weekly alcohol = 12.9 units in 11-15 year olds in 2010 (49). After taking into account prevalence, this is equivalent to 5 million units a week, or 0.6% of alcohol sales. For 2010 this would add 0.12L to per capita consumption.

A 2013 UK study by Meier et. al. estimated consumption by children to account for 0.7% of UK alcohol sales, or to subtract 0.08L to per capita sales (48).

Legal imports, illegal imports, informal production and homebrew equivalent to 175 million units a week in England in 2010. HMRC has a strategy to tackle alcohol fraud but information is lacking (53, 54).

Personal correspondence with the Craft Brewing Association, the National Association of Wine and Beermakers, and homebrew online shops has confirmed there is no estimate of homebrew available for the UK.

Drinking by people outside sampling frame: homeless

A 2013 UK study by Meier et. al. estimated this to have an effect of +0.08L on per capita survey estimates (48).

50,430 households were in temporary accommodation in March 2012 (55). If each household contained two adults this is equivalent to 0.2% of the adult population in 2011.

A London-based homelessness charity estimates there are up to 17,000 street drinkers in England drinking on average 45-70 units a day (56). This is equivalent to 0.01% of the adult population in 2011. However, not all street drinkers are necessarily homeless/would be outside the sampling frame. Counterfeit production

None available. This is of increasing concern to the industry; the Wine and Spirits Trade Association launched a fraud prevention unit in May 2011 (57).

Drinking by people outside sampling frame: people living in institutions

This includes those in the armed forces, hospital, residential care etc. Students in halls of residence are included in GLF.

A 2013 UK study by Meier et. al. estimated this to have a net effect of -0.041L on per capita survey estimates (military = +0.006L, mental health institutions = -0.003L, care homes = -0.034L, and prisons = -0.010L) (48).

A 2004 review on measuring alcohol consumption stated that the distribution function of alcohol suggests that very small subgroups could be responsible for a considerable proportion of the missing units, so further research on heavy-drinking

subgroups not traditionally sampled is necessary (58). Consumption of non-beverage alcohol

e.g. antibacterial handwash.

None available

36

Meier et. al.’s 2013 study uses 2006 data and per capita consumption estimates for key countries and estimates the net impact of tourism to be 0.86L (48).

Consumption by UK residents overseas

595 million nights spent abroad in 2011 (59). See opposite column for net effect.

Using average consumption to estimate consumption while abroad may under-estimate the effect of tourism. A 2011 survey by the world's largest travel website of 6,671 respondents in France, Italy, Germany, Spain and the UK found 65% of British people drink more on holiday than at home, compared with a European average of 41% (60).

One study estimated the UK’s net consumption on journeys abroad to be 0.2l per adult aged 15+, and tax free purchases to be equivalent to 0.23L per adult aged 15+

in 1995 (51). This is equivalent to 20 units of alcohol. This was equivalent to 2.7% of alcohol sales for 1995, which would be equivalent to 0.6 units per adult per week today.

Non-responders to surveys

The continuum of resistance theory suggests non-responders are more likely to share characteristics with late responders to surveys, who have been shown to be heavier drinkers (33, 61, 62) (also see Section 2.6.2).

A 2013 UK study by Meier et. al. estimated this to have an effect of +1.24L on per capita survey estimates (non-responding groups estimated were: students = +0.03L, dependent drinkers = +1.01L, proxy interviewees in GLF = +0.20L) (48).

Non-response to surveys is described as a weak justification of low alcohol sales coverage in Section 4.6.

Alcohol that is bought but not consumed

Includes that which is used in cooking, disposed of as reaches expiry, spillage/wastage, stockpiling or storage.

A 2013 UK study by Meier et. al. estimated this to have an effect of -0.82L on per capita survey estimates (spillage/wastage = -0.76L, food use = -0.06L) (48).

Industry estimate for spillage/wastage is <10% (47), DEFRA estimates 6%, which is equivalent to 0.64L (63).

Net effect of storage/stockpiling needs to be considered as previously stockpiled alcohol may be being consumed.

Consumptio n of non- beverage alcohol

e.g. antibacterial handwash.

None available

37 Alcohol sold but not captured in social surveys

(for reasons other than under-reporting)

Alcohol consumption not captured in alcohol sales statistics

Description Estimate Description Estimate

Sampling periods not representative Sampling periods for social surveys often exclude holiday periods and Christmas,

when consumption is probably much higher (61, 64), however the GLF sampling took place all year round.

Clustering

There is some evidence that heavy drinkers are clustered in geographical areas making them less likely to be sampled (33, 62). This means that heavy drinkers may be under-represented in survey samples.

Alcohol cleared for sale but not sold

None available

Estimated total alcohol included in sales figures but not captured by surveys: between 1.9 and 2.1 litres per capita

Estimated total alcohol not included in sales figures: between 2.1 and 2.9 litres per capita

Footnote to table: it is also possible that over-reporting of alcohol consumption occurs. This may take place, for instance, among relatively light drinkers who wish to adhere to social norms, or due to peer pressure (for example among young men). Investigating over-reporting of alcohol consumption was beyond the scope of this thesis. This thesis is interested in understanding reasons for low alcohol sales coverage, which is not explained by over-reported alcohol consumption.

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