The BBC website published a worrying article today about actual vs. self-reported alcohol consumption.
“University College London researchers compared alcohol sales figures with surveys of what people said they drank.
They found there was a significant shortfall with almost half of the alcohol sold unaccounted for in the consumption figures given by drinkers.”
It’s a great reminder of why you’ve got to choose your methodology carefully.
Asking how people much they drink has three major flaws.
First, people find it hard to remember what they drank, and many people don’t understand what a unit of alcohol is.
Second, people want to be viewed favourably by others, and don’t want to admit to socially undesirable behaviours. The social desirability bias.
Third, they may also have a vested interest in under-estimating what they drink. It can be easier not to face up to things.
GPs know this. A medic friend says he doubles the self-reported alcohol consumption data given to him by patients. He’ll be glad to hear his rule of thumb confirmed by the UCL survey.
The Drinkaware trust know this. They realised that – whatever you say or admit to yourself – the contents of your recycling bin doesn’t lie. Their 2008 campaign uses behaviour to confront attitudes.
Behaviour (sales data), is more powerful than attitudes (what people say) if we’re interested in an activity with strong social norms like alcohol consumption. Attitudes have more of a role to play in explaining why.
I for one want to know what lies behind drinking behaviour, and how social norms differ by tribe. Overlaying attitudes and context should get us there.