Cut out statistical fallacies. Counting the dead is serious business

Subtracting the crude death rate from the crude birth rate provides the rate of natural increase, which is equal to the rate of population change in the absence of migration.

In ordinary circumstances, as the World Bank points out, the crude death rate serves as a good mirror to gauge the general health status of a country. Higher crude death rates can be found in some developed countries, despite high life expectancy, because typically these countries have a much higher proportion of older people, due to lower recent birth rates and lower age-specific mortality rates.

A long term secular decline in the crude death rate, such as in the case of India and many others, generally, shows people have gradually become healthier over decades, assisted by better health services and infrastructure.

Birth rates and death rates, which form the core pillars of vital statistics, are a critical national information resource for understanding public health. These data are based on data from birth and death registration systems, censuses, and sample surveys by national statistical offices and other organizations, or on demographic analyses.

But what happens in an extraordinary year such as the Covid-19 pandemic that devastated the world, dealing a debilitating blow on lives and livelihoods, and causing millions of deaths spread over two years, and still counting?

How many people have died of Covid-19 in each country? Specifically, how many people have died of Covid-19 in India during 2020 and 2021? These questions lie at the heart of the dispute over the World Health Organisation’s (WHO) Covid-19 death data.

Ideally, these will show up in a sharp spike in official death statistics.

The WHO, in a report on excess Covid-19 mortality, has estimated 4.74 million deaths for India in 2020 and 2021, nearly 10 times higher than the country’s official coronavirus toll of 484,000 during the two years. India, according to the report, had the highest excess COVID-19 deaths, followed by Russia and Indonesia.

The WHO said it used a combination of national and local information, as well as statistical models, to estimate totals where the data is incomplete, a methodology that India has criticised.

There are two basic issues with the data. One, for death data to be under-reported by a multiple of 10, there has to be near synchronised under-reporting by all state governments and the central government. This would imply that all state governments, irrespective of whichever party was or is in power, have under-reported Covid-19 deaths.

These need thorough verification. There were deaths that were “registered” Covid-19 deaths, and there were “unregistered” or hidden Covid-19 deaths. These need to be resolved through a field-level complete enumeration to reconcile Covid-19 death data. These will then have to be tallied with data from crematoria and burial grounds to match what has been collected from the field level data. There will still be gaps, because many families would have not reported Covid-19 deaths in their families and buried the bodies on river banks as was seen in many images last year.

The second aspect has got to do with India’s social structure, which makes it difficult for families to hide deaths. In normal circumstances, because of the elaborateness of the rituals, a death in any family involves a gathering of people. Without a complete enumeration engaging field- level surveyors and data collectors, under-reporting of Covid-19 deaths of such a large scale will be difficult to capture.

Statistical modelling and extrapolations based on past trends can give good approximations of death data during normal years. These can, however, be fallacious during pandemics such as the Covid-19 where there were no previous instances and bio-statistical analysis to frame hypotheses for rigorous statistical testing.

Under-reporting of deaths by a multiple of 10 will eventually have to show up in the crude death rates of those years. This, as previously stated, will require a door-to-door enumeration. This will be time consuming, but worth the effort for the sake of public health and data in India. Until then, all estimates are just that, estimates.