To the Editor: President Donald J. Trump’s tweet denigrating Ambassador Marie Yovanovitch during her recent Congressional testimony is reminiscent of an incident that occurred in Czarist Russia during the 19th century.

My recollection of the story is that a pandemic was spreading throughout various parts of the country. In response to this situation, the Czar’s government dispatched teams of doctors to places where the outbreaks were especially severe.

Certain groups of peasants observed that the outbreaks were most severe where the teams of doctors were on scene.

One can construe this simply as a statistical correlation between the number of doctors and the number of deaths that occurred at a particular site. Tragically, the peasants, sensing a causal connection, assigned responsibility for the deaths to the doctors and proceeded to execute some of them.

This horrific tale of woe is sometimes used to illustrate the difference between causation and correlation in statistical texts.

Unfortunately, in his tweet the President seemed to imply that Ambassador Yovanovitch was somehow responsible for the deplorable conditions in the foreign service posts to which she was assigned. Mr. Trump, for example, specifically mentioned her service in Somalia — cited by the World Population Review as the most corrupt country in the world. Ambassador Yovanovitch — like the Russian doctors — was not the cause of the conditions that existed before her arrival at her posts, but was sent to ameliorate them.

CHARLES V. A. WHITE

Londonderry

CHARLES V. A. WHITE, Ph.D.

Professor of Economics, Retired

Southern NH University

Londonderry