Roemer and colleagues found a positive correlation between the number of short-term general hospital beds available per 1,000 population and the number of hospital days used per 1,000 population.
[3][page needed] The law is thought to be a consequence of induced demand: physicians encouraging patients to consume services that the patients would not have chosen if they had been fully informed.
"One problem in this finding is that it could be the case that hospital stays are shorter in lower hospital bed per capita regions because of a deficit in supply (reverse causation).
An increased number of beds may be due to patient preference for in-patient (rather than outpatient) care in a region.
"[5][self-published source] Enoch Powell, the British Minister of Health, propounded a similar proposition, which he called Parkinson's law of hospital beds: "the number of patients always tends to equality with the number of beds available for them to lie in.