A study in the Christmas issue of The BMJ dispels the myth that Santa Claus rewards children based on how nice or naughty they have been in the previous year.
Instead, the results suggest that socioeconomic deprivation seems to play a greater role in determining a visit by Santa Claus, with children in hospitals in the most deprived areas less likely to receive a visit.
The researchers say further studies are needed to examine whether Santa Claus actively discriminates or whether deeper structural factors are at play.
It has long been thought that Santa Claus gives presents to nice but not naughty children. However, no evidence exists to support this - or to establish whether this is the only factor determining the likelihood of a visit from him.
So a team of UK and US based researchers set out to determine which factors influence whether Santa Claus will visit children in hospital on Christmas Day.
They surveyed every UK hospital with a paediatric ward to find out if Santa had visited during Christmas 2015.
They then correlated this with rates of absenteeism from primary school, conviction rates in young people (aged 10-17 years), distance from hospital to North Pole, and socioeconomic deprivation.
Santa Claus visited most of the paediatric wards in all four countries: 89% in England, 100% in Northern Ireland, 93% in Scotland, and 92% in Wales.
The odds of him not visiting, however, were significantly higher for paediatric wards in areas of higher socioeconomic deprivation. In contrast, there was no correlation with school absenteeism, conviction rates, or distance to the North Pole.
The researchers are unable to explain why this association exists, but one possible theory may be that Santa Claus is forced to sustain existing inequality, as he is contractually not allowed to change anyone's socioeconomic status.
"It has long been thought that Santa Claus gives presents to nice but not naughty children," say the authors. "This is the first study, to our knowledge, to dispel the myth that Santa visits children based on behaviour and suggests socioeconomic deprivation plays a greater role in determining a visit."
"Undoubtedly deeper socioeconomic factors are at play, even impacting Santa Claus's abilities to reach out to every child," they add. "Whether his contract needs to be reviewed or local Santas employed in "hard to reach" areas, all we want is for every child to be happy this Christmas," they conclude.
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About The BMJ Christmas editions
The BMJ publishes special issues of the BMJ over Christmas and New Year. All submissions follow the standard requirements for The BMJ's articles, and go through the usual peer-review processes. Each paper uses proper research methods and stands up scientifically.