When a small city only has two Emergency Departments, you can run a study like this to see what effect publication of ED wait times has on visits.
While it is fabulously logical that if 18 to 40 people a day are looking at your Emergency Department wait times that some portion of those people will choose a facility with a shorter wait time – or choose not to come to the ED at all – or choose to come in when they might not have otherwise come in if the wait time is short – this study doesn’t actually try to study the population of interest. They need to somehow capture individuals who are using the published information to make decisions, rather than looking generally at their overall wait time statistics – because, even though they say their results “were consistent with the hypothesis that the publication of wait time information leads to patients selecting the site with shorter wait time”, they are making a huge unsubstantiated leap.
Looking at their descriptive statistics, hardly anything changed to actually justify their conclusions, and, really, it looks like patients just based their decisions pretty heavily on which of the two hospitals was closer – particularly Victoria Hospital, which people only went to if it was nearer. I do also find it fascinating that their mean wait time rose from about 105 minutes to 115 minutes, yet the amount of time their wait time was >2 hours (120 minutes) actually dropped from 13% to 9%. This is how they justify their conclusion that the “spikes” are mitigated by online usage – and it may be true – but there are too many moving parts and they aren’t actually asking people if they used the website and used the information from it.
“The effects of publishing emergency department wait time on patient utilization patterns in a community with two emergency department sites: a retrospective, quasi-experiment design.”
http://www.ncbi.nlm.nih.gov/pubmed/21672236