Evidence-Based Management

What a 19th Century Physician and an NFL Offensive Guard can Teach Us

By Dr. Richard R. Reilly, Emeritus Professor, School of Business, Stevens Institute of Technology

Leaders often operate on the basis of “accepted wisdom,” ideas that persist despite a lack of real scrutiny. Two interesting examples of challenges to accepted wisdom can be found in 19th century Vienna and the 21st century NFL.

Using Evidence to Save Lives: Ignacz Semmelweis

Ignacz Semmelweis, a physician in Vienna in the 1840s, was disturbed by the high death rate for mothers due to postpartum infections in his obstetrics clinic. He noticed that there was a much lower death rate in a second clinic, which was staffed by midwives. Semmelweis began gathering data to compare the two clinics and found that the clinic staffed by physicians had a consistently higher death rate—sometimes a much higher death rate—than the clinic staffed by midwives.

He knew that in his clinic physicians went directly from examining cadavers to assisting in childbirth without so much as washing their hands—though shocking to us now, this was the accepted practice of the time. The midwives, on the other hand, were never in contact with cadavers. Semmelweis reasoned that there was a connection between contamination from the cadavers and the infections sustained by the mothers. Once he required his physicians to sterilize their hands with a bleach solution before delivering a baby, the deaths from postpartum infection at his clinic dropped to near zero.

You might think that his physician colleagues would have welcomed his findings, but instead his ideas were roundly rejected and he was vilified.

Using Evidence to Gain Points: John Urschel

John Urschel was an offensive guard for the Baltimore Ravens in the National Football League.  Urschel was unusual because he was an elite professional athlete who was simultaneously pursuing his Ph.D. in mathematics at MIT. In American Football, after scoring a touchdown, the scoring team can try for one point by kicking or two points by a conversion, getting the ball in the end zone. Urschel wondered if there was a statistical reason why NFL coaches rarely tried for two points, so he looked at the data. The average success rate of kicks was 94% yielding an expected point value of .94.  He reasoned that you only needed a two-point conversion rate of .475 to get a higher expected point value (.95). It turns out that in 2019 the two-point conversion rate was 60%, yielding an expected point value of 1.2. Despite this pretty clear evidence that they would gain a competitive advantage by opting for conversions, NFL coaches still prefer to kick for one point after scoring a touchdown. In other words, they prefer to continue using accepted wisdom even though there is a clear statistical advantage for doing otherwise.

Using Evidence to Confront Common Business Assumptions

As with football and medicine, business leaders often operate on the basis of accepted wisdom.  For example:

But are these firmly held convictions really valid?

A review of 220 studies on the influence of equity incentives concluded that there is little evidence that equity incentives of any kind, including stock options enhance organizational performance.

The research evidence on first mover advantage is quite mixed. In fact, it is often the third or fourth mover that wins.

A survey of 200 HR executives reported that forced ranking resulted in lower productivity, inequity, skepticism, decreased employee engagement, reduced collaboration, damage to morale and mistrust in leadership.

The Semmelweis Reflex and Business

The story of Ignacz Semmelweis led to recognition of a cognitive bias called the Semmelweis Reflex, a generalized tendency to reject new evidence that contradicts an established paradigm.  Evidence-based management, where leaders are presented with objective criteria for decision making, often produces the Semmelweis Reflex for several reasons.

First, managers have a strong preference for intuitive decisions and contrary evidence may be threatening to their status. James Barksdale, former CEO of Netscape (remember Netscape?) said, “If the decision is going to be made by facts, then everyone’s facts, as long as they are relevant, are equal. If the decision is going to be made on the basis of people’s opinions, then mine count for a lot more.”

Second, many managers distrust statistics and research findings. They perceive academics, who do most of the research, as living in “Ivory Towers” vs. the real world of business. They feel their personal experiences are much more powerful, even though they may be anecdotal.

A third factor is cultural cognition, the influence of group values on related beliefs. Managers tend to follow the lead of others just like them. There is a strong bias for prior or prevailing practices.

Fourth, organizational cultures often reward quick intuitive decisions and the feedback loop may be long or non-existent.

Using objective measures to assess business decisions and behaviors seems like it would be a no-brainer, yet because of the reasons listed above, most who want to implement an evidence-based approach to leadership will find themselves frequently met with the Semmelweis Reflex. Before instituting evidence-based management practices, consider how you’ll respond to this resistance.

Take Action

Leaders interested in developing an evidence-based management approach may find that they need to overcome the Semmelweiss Reflex in their own workplaces. Below are some actions they can take:


Giluk, T., Rynes-Weller, S. (2012). Practitioners resist: Lessons for Management Academics from

Evidence-Based Management.  P.130-164. In The Oxford Handbook of Evidence-Based Management, Oxford Library of Psychology.

Loveman, G. (2003).  Diamonds in the data mine. HBR Best Practice, 109-113..

Pfeffer, J, Sutton, R. (2006). Evidence based management.  Harvard Business Review, January.

Nuland, S.B. (2013). The Doctor’s Plague: Germs, Childbed Fever, and the Strange Story of Ignacz Semmelweis. W.W. Norton, New York.