Wait a minute

Astatistics professor of ours said that extremes in data pull the mean by the tail. The data here is how many days it takes New Yorkers to get their coronavirus test results. The extremes are the far too long times it’s taking some of us to learn whether we are infected or not.

Of the thousands of daily tests run in this city by public hospitals or clinics or walk-in urgent care storefronts, the median wait for results — a number oft-cited by city officials from the mayor on down — is three days. Thus half of the people get answers in three days or less, and half take longer.

Which tells you something, but not nearly enough.

We queried top city doctors for the mean, or (back to stats class) the average you get by adding up all wait times and dividing by the total number of tests. They cautioned that the average was big.

Right they were: 11 days. So, thousands of people who get tested don’t get their results quickly enough to make self-quarantine feasible, risking COVID spread in the meantime. Not good. Most long delays involve big commercial outfits without in-state labs.

Officials also report that the 75th percentile is 11 days. Translation: While half find out in three days or less, a quarter hears back in three to 11 days and worst of all, another quarter has to wait 11 days or more. Worse, the 75th percentile was eight days in July, so it’s getting even longer.

And the stats powerfully suggest that a sizable share of wait times are far, far longer than 11 days.

Our Rx: Require every testing site to publicly post, online and in its window, its current average time for results. Averages that people who haven’t studied statistics can understand.