A headline in the Washington Post (April 26, 2020), based on the researchers’ conclusions at the time, blared, “In New York’s largest hospital system, 88% of coronavirus patients on ventilators didn’t make it.” (As of April 25, the headline wasn’t corrected. By May 5, it had been changed to read “…many patients on ventilators didn’t make it.”)
This is one example — the cornovirus pandemic has provided many — of the importance of proper denominators.
Denominators often are not scrutinized closely enough by journalists, by businesses, or by wellness professionals. The gross oversight described here reminds us that, without any background in statistics or data science, denominators used in calculations — when, indeed, they are used — are one reasonable starting point (population size is another) when interpreting data.