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How Certain Are You About Uncertainty? A Knighted British Statistician Knows Your Limits

Professor Sir David Spiegelhalter at play

Ask a statistician to explain a coincidence and you will hear something like:

In large populations any strange thing can happen.
You remember only the personally charged coincidences and don’t notice the many other coincidences happening around you.

Professor Sir David Spiegelhalter is no exception. He loves coincidences. He loves studying coincidences. His website Understanding Uncertainty has collected more than 4000 coincidence stories for him to mull over. He marvels at their frequency in people’s lives and how they understand and use them. He rarely notices them himself. He wants to convince you that statistics offer the best explanation.

A Brief Bio
Sir Spiegelhalter aims to improve the way statistical evidence is used by health professionals and patients. He advises organizations and government agencies on risk communication and is a regular media commentator on statistical issues, with a particular focus on communicating uncertainty.

He is the author of Sex by Numbers, and The Art of Statistics. He was elected Fellow of the Royal Society in 2005, knighted in 2014 for services to medical statistics, and was President of the Royal Statistical Society for 2017-2018.
He considers himself a policeman of science whose job it is to make sure that data suggesting a pattern really show demonstrate a pattern. Apophenia, seeing patterns that aren’t there, is one of his favorite words. Valuable contributions!

He helps medical patients understand the probabilities involved with the prognosis of their diseases. Very important because physicians and nurses are rarely trained in probability.

A Cluster Analysis

The Quid group analyzed the content of the stories on his website. They found:

Sharing a birthday with someone (11%)
Probability easily explains sharing a birthday—you have a 1/365 chance of that happening. It has to happen.

Connections involving books, TV, radio, or the news (10%)
Connections involving books and media was difficult for Sir Spiegelhalter to explain. Media coincidences commonly occur by respondents to the Weird Coincidence Survey.

Vacation-related coincidences (6.1%)
Running into someone you know on vacation can be explained by both of your being in a similar socio-economic group that travels to similar vacation spots.

Meeting people in transit—while walking around, in airports, or on public transportation (6%)
They may be people you know, and people who become meaningful to you.

Coincidences related to marriage or in-laws (5.3%)
Coincidences related to family members, covers a wide variety of possibilities including Simulpathity (feeling the pain of a loved one at a distance)

Professor Spiegelhalter would like you to believe that statistics provide the best explanation for all of these coincidences. Would he consider the conventionally accepted psychodynamic explanation for some of them?

He reported his own remarkable coincidence:
“I was on a radio show working with several people. I was choosing a date since one of my favorite coincidence stories was about matching birthdays, and I had forgotten the date. I paused for a moment and picked this date. It matched the birthdays of 2 of the people with whom I was working. The probability that they had the same birthday was 1 in 365, and the probability that my ‘random’ choice matched it is 1 in 365, making it about 1/ 135,000 ( 1/365×1/365 = 133,225).

To listen to his lively exchange with me, click here

Synchronicity and Symbols: We live in a symbolic matrix

Norse Tree of Life

I am developing a taxonomy for coincidences. Early botanists noticed similarities and differences among plants and categorized them; I’ve noticed similarities and differences among and between the coincidental flora in the forest of daily life.

To develop a scale for coincidence sensitivity, I asked participants to rate the frequency of common coincidences. The list of common coincidences was gleaned from a much longer group of possibilities. The result was the Weird Coincidence Survey. The 12 items of the WCS can be found on this website under “your coincidences”. You can take the survey to see how sensitive to coincidences you are.

From 1551 respondents to the WCS, the most common coincidences were:

I think of a question only to have it answered by an external source (i.e. radio, TV, or other people) before I can ask it.
I think of an idea and hear or see it on the radio, TV, or Internet.
I think of calling someone, only to have that person unexpectedly call me.
I advance in my work/career/education by being in the right place at the right time.

Most intriguing to me are the connections to our media. Are we becoming nodes in the vast internet connectivity? I explore this idea in this PT post.

Ray Grasse has a grander view. He starts with synchronicity and then expands to the symbols all around us. He notices what happens at the beginning of a process. One of his examples involves two people meeting for the first time and a car exploding outside as they talk. Foreboding for the relationship! And it was. The relationship did not go well.

Grasse quotes Emerson: “The whole world is an omen and a sign. Why look so wistfully in a corner? The voice of divination resounds everywhere and runs to waste unheard, unregarded, as the mountains echo with the bleatings of cattle.” (The Waking Dream, p.251)

You see a car on fire, a knife injures your foot, you have an argument with your spouse and Mars is in transit. Each of these has in common a force of some kind. To hear Ray talk about the expansion of symbol awareness in daily life please click here


Grasse, Ray. The Waking Dream (1996): Unlocking the symbolic language of our lives. Quest Books. Wheaton, Ilinois, USA