A leading academic has re-examined the "minefield" of statistics comparing Covid-19 death rates north and south of the border and concludes new data suggests Northern Ireland fatalities are "well above" those in the Republic.
Emeritus Professor Mike Tomlinson, who retired from Queen's University three years ago following a distinguished career in social policy, has discovered information his counterparts are using in the Republic and set them aside "gold standard" data measuring the impact of a pandemic on excess deaths in the north.
He says that a casual comparison of 'official' figures would "lead you to believe" that the Republic's rate - at 302 deaths per million people - is much higher than the north's (at 239).
However, using the Northern Ireland Statistical and Research Agency (NISRA) data, Professor Tomlinson examines the ‘excess death’ count – which are the number of fatalities occurring that are “over and above” what might be expected at this time of year, based on the average for the previous five years.
Up until May, this figure stands at 766.
“This is regarded as the ‘gold standard’ for assessing the impact of an epidemic or other exceptional event on mortality,” he writes.
While there is no comparable details for the south, he turned to the work of the economist and lecturer, Seamus Coffey, who is based at University College Cork, and has carried out detailed research using an an online database of death notices (RIP.ie).
Mr Coffey has “cleaned” this data, and then taken every quarter and plotted it against the official Central Statistics Office (CSO) mortality records for the Republic so see “how well it stands up as a substitute” - as the CSO figures take so long to produce.
"I've looked at Coffey's numbers and they stand up as far as I'm concerned. His use of that data is a useful match to examining excess deaths in the Republic and it's a good enough estimate of the true death certificate registration figures," he said.
"Coffey has shown that there is a remarkably close relationship between the official count of registered deaths and RIP.ie notices going back over five years," Professor Tomlinson said.
"This means we can compare north/south excess deaths using the proxy. The graph compares excess death rates at four dates, based on cumulative totals. At every point the north’s rate is well above the Republic’s - between 41 and 50 per cent above."
Professor Tomlinson wrote an article in The Irish Times last month which also pointed to the north's Covid-19 mortality rate being up to 50 per cent higher than the Republic's.
While public health experts praised the piece, there was some criticism due to the lack of available data in analysing the two jurisdictions - which the Queen's academic stressed was an issue at the outset.
Concerns around transparency in the north have been raised throughout the pandemic, with the UK Statistics Authority admonishing the Department of Health last month over "gaps" in its information.
Professor Tomlinson said he understood that statistics were "never perfect" but that they must be used in the debate around policies, such as testing, as we exit lockdown.
"I believe in the importance of social statistics, they're never perfect and it's important we understand their imperfections," he said.
"The purpose of the original Irish Times article was to take two jurisdictions that had adopted very different policies in terms of lockdown and particularly in terms of testing strategies. I asked the simple question: Has this resulted in a different outcome in terms of deaths? It appeared to me there was very strong evidence that it had."
The academic said he also believes the only way out of lockdown was to have an all-island approach, particularly on testing, contact tracing and isolation.
"If you don't know where the virus is, then you never going to end up controlling it or putting the fires out. The danger with having different policies north and south is that the fires that spike up in the north will contaminate the south," he added.
"As unlock progresses, the dangers gets even greater of not having a co-ordinated approach and not treating the place as a single unit."
