DO THE MATHS

Once again, OCTA Research has opened itself to accusations that it may be peddling misinformation on Covid-19 when it came up with a wildly off fatality rate from the virus for Metro Manila at 5.4 percent.

While its members from the academe, like those from the University of the Philippines and University of Santo Tomas, have lofty credentials, they still have to show how they arrived at that figure compared to the 1.46 percent of the Department of Health (DoH).

There is no mystery as to how DoH computes fatality rates and other Covid-19 statistics like the virus’ reproduction rate because the agency has aligned its methodologies with those of the World Health Organization (WHO).

It is to DoH’s credit under Secretary Francisco Duque III that it set a meeting with OCTA Research to discuss, presumably with an open mind, their varying computations on the coronavirus fatality rates in the National Capital Region.

Before shooting from the hip and accusing OCTA of mucking up the figures (some have claimed this group to have an anti-government agenda), the DoH, as a science-based agency, wanted to see the maths that led to the 5.4 figure.

OCTA has a lot of explaining to do and it has fumbled the ball even before that powwow with the DoH can materialize. A member, Butch Ong, said the wide disparity may have to do with their “mathematical assumptions” and “elements” with emphasis on theirs.

While he claimed OCTA is also using the same data used by the DoH, Ong averred that “maybe the difference is on the averaging of the data.”

“Probably, it’s in some of the mathematical assumptions and some mathematical elements used by OCTA and the DoH. But both of us are working to advise on policy to keep people informed,” he said.

For those presumably trained on numbers and certainties and formulas, members of OCTA seemed predisposed to “maybes” and “probabilities.”

While there is room for assumptions in mathematical modeling, when it comes to fatality rate, there is very little room or variance in computing it. We don’t know what averaging of data or mathematical assumptions can lead to the vast difference between the 5.4 percent of OCTA and DoH’s 1.4.

And no, OCTA cannot assume to be doing work similar to the DoH in terms of giving advice on policies and in informing the people. It cannot just pluck numbers from thin air using unvetted formulas.

The wide disparity between the fatality rates of the DoH and OCTA for Metro Manila was for the period 28 March to 13 April, with the latter’s 5.4 percent, nearly three times the 1.82 percent from 1 to 27 March.

Were the DoH and OCTA figures for March the same? If yes, then there can be no plausible explanation for the disparity in the April figures. If OCTA’s March fatality rates have not been tracking the DoH’s, then how come, over a year into this pandemic, this group has not laid bare its system of computations and the variables it uses?

Maths and science are supposed to be exact fields of discipline, so it is unlikely that — using the same variables and numbers — figures computed by two different sets of experts will not jibe.

DoH Undersecretary Maria Rosario Vergeire gave OCTA’s members the benefit of the doubt when she said statisticians tended to use various numerators and denominators to determine fatality rates, acknowledging that epidemiologists tend to have “different opinions.”

She stressed, however, that the DoH’s computations are based on the formula set by the WHO and the US Centers for Disease Control and Prevention. Based on that formula, all confirmed cases, including deaths, recoveries and active cases, form part of the denominator.

The USCDC defines case mortality rate as the measure of the frequency of occurrence of death in a defined population during a specified time.

OCTA’s computations are based on what? On an agenda to paint a bleak picture on how the government is handling the health crisis? It will be interesting to know what groups and personalities are behind OCTA and where it gets its funding.

It cannot be providing forecasts, analyses and supposed trends in pandemic figures unless its primary movers are identified, especially since media firms have been quoting its reports freely.

Malacañang cannot be faulted for looking at OCTA with suspicion especially when it comes to figures that its supposed experts cannot explain.

“There is no mystery as to how DoH computes fatality rates and other Covid-19 statistics.

“It will be interesting to know what groups and personalities are behind OCTA and where it gets its funding.