The “Directionally Correct” Fallacy, Part II: What is “Directionally Correct”?
“Directionally correct” is the most overutilized and pernicious phrase in healthcare. Merriam-Webster does not define the phrase but does define the word “directionally” this way: “as to or with reference to direction,” violating the adage that it is inappropriate to define a term by referencing that term.
Turning to the Internet, it is particularly noteworthy – and ironic – that the first result of a Google search of “directionally correct” returns a Forbes article titled “How To Speak McKinsey: 15 Key Phrases To Pass Yourself Off As A Top Management Consultant,” in which the phrase is defined this way:
Translation: The analysis is correct in its broad conclusions.
Real meaning: The analysis is incorrect in some of its numbers.
More precisely, “directionally correct” is defined this way:
“Directionally correct is an expression used to indicate that a measurement is accurate to the extent that it shows the quantity to be measured to be positive or negative even though the degree to which the quantity is positive or negative may be measured inaccurately.”
Healthcare executives frequently say that information is “directionally correct” when referring to physician referral patterns or market share growth projections, by which they mean that reality is not completely opposite from the observed trend. And so, it is “directionally correct” to assume that surgical care is migrating from inpatient settings to outpatient settings. How much? Who knows?
Whatever “directionally correct” means, it is vastly different from a quantitative approach based on “probability,” which the Oxford English Dictionary defines this way:
“The extent to which an event is likely to occur, measured by the ratio of the favorable cases to the whole number of cases possible.”
In thinking about how healthcare industry executives are appeased by “directionally correct” information in making strategic decisions, I am reminded of C.S. Lewis’ words about being “far too easily pleased.” Implicit in every statement that a data point is “directionally correct” is a fatalistic admission that the available data is insufficient to support an informed decision. Over time, these uninformed decisions have a compounding effect that makes winning a losing game virtually impossible. In Part V, we will explore the financial and legal risks of a continued reliance on the “directionally correct” fallacy.
 Lewis, “The Weight of Glory,” p.1