Mapping PGSI data in Great Britain: A note on data analysis
A note on the data analysis and methodology used can be found below.
In order to produce maps at local authority and ward level, researchers at YouGov used multilevel regression and post-stratification (MRP). MRP is a method used to estimate public opinion or behaviour by taking the observations from a sample of participants and applying these to the wider population. MRP is based on the premise that similar people hold similar views and exhibit similar behaviours, irrespective of exactly where they live. The researchers built a model using data about the demographic make-up of a particular place and matched individuals from the pool of survey respondents with the types of people that live there.
It is important to note that this analysis produces rough estimates only. MRP is not intended to produce an accurate figure for each locality, but rather to give indicative estimates that then provide a sense of how PGSI prevalence and usage and reported demands for treatment and support is spread across the country, in relative terms.