Dear Mr Humpherson,
I write to raise concerns about a press release from a new Scottish Government agency, Public Health Scotland, published on 10 June 2020. It was issued with a report containing a statistical analysis of the impact of Minimum Unit Pricing (MUP) on off-sales of alcohol in the first year after the policy was introduced on 1 May 2018.
The news release states that, in the twelve months after the introduction of MUP, off-licence and retail sales of alcohol in Scotland decreased by between 4 and 5% when compared with England and Wales. The news release does not say how the level of such sales changed when compared with off-sales in Scotland itself in the 12 months before MUP was introduced – not even in a footnote. Even more surprisingly, the actual change in levels of sales in Scotland is also omitted from the report published at the same time.
This presentation quite predictably led journalists to report that there had been a fall in off-licence sales in Scotland of between 4 and 5%, thanks to the introduction of MUP. That in turn led other reputable individuals to comment on the story as if there had indeed been such a large fall, because the actual figures were not made available.
The actual figures seem to have emerged only in an interview given by Lucie Giles, Public Health Intelligence Principal at Public Health Scotland, to BBC Radio Scotland’s Good Morning Scotland on the morning of 10 June. She told the interviewer that the actual reduction in off-licence and retail alcohol sales in Scotland was 2.6% during the first year after MUP was introduced, and that there was an increase in sales over the same period in England and Wales of 2.3%. “Incorporating the figures into a single model, using England and Wales as a geographical control,” she said, “that’s how we have come to those figures of a net reduction of four to five percent.”
There is nothing intrinsically wrong with comparing a 2.6% reduction in Scotland with a 2.3% increase in England and Wales, and suggesting possible explanations for the difference. There may be issues about adding these two numbers together, given that the market for alcohol sales in England and Wales is quite different in scale from the market in Scotland: but a combined figure of this kind could have been presented with the appropriate caveats.
That did not happen. Nobody, as far as I know, other than listeners to Good Morning Scotland at the relevant time on the day of publication, will know how far sales in Scotland actually changed from one year to the next, far less how the published figure of “between 4 and 5%” was reached. Most people are bound to assume that the figure presented actually represents the fall in off-sales in Scotland.
The Glasgow Times for example reported: “According to the report by Public Health Scotland, minimum unit pricing (MUP) could be attributed to a reduction in alcohol consumption per head in Scotland of between four and five per cent overall in the 12 months from May 2018.”
STV, on the other hand, mentioned that the figure was in comparison with England and Wales, but did not make clear what this actually meant. Their story quoted Alison Douglas, chief executive of Alcohol Focus Scotland, who said: “A reduction of between four and five per cent in off-sales in the 12 months following the introduction of MUP is really significant.”
None of the outlets I checked or authorities I saw quoted gave the actual figures for the fall in consumption in Scotland, because that information was not presented to them. It is disappointing that a public agency chose to present statistics in such a misleading way, so that even expert witnesses concluded that the fall in off-sales of alcohol following introduction of MUP was nearly twice as large as it actually was. Given that Public Health Scotland is a new agency, with many important responsibilities, I would encourage you to draw the principles of best practice in the use of statistics to their attention.
I attach below links to the PHS news release, and to the news reporting I have mentioned.
Lewis Macdonald MSP
North East Scotland