Cambridge Coincidences Collection

As of the 23rd May 2022 this website is archived and will receive no further updates.

understandinguncertainty.org was produced by the Winton programme for the public understanding of risk based in the Statistical Laboratory in the University of Cambridge. The aim was to help improve the way that uncertainty and risk are discussed in society, and show how probability and statistics can be both useful and entertaining.

Many of the animations were produced using Flash and will no longer work.

Well I Never!

Professor David Spiegelhalter of Cambridge University wants to know about your coincidences!

One Billion Birthdays

I am currently staying in Mumbai, India at a women's hostel. In my first few days of arriving my roommate was helping me to get some information sorted to be signed up for internet services. As I do not speak Hindi she was the middle-person giving my address, name and birthday over the phone. Suddenly she smiled really big and exclaimed, "you were born 17 July?!" I nodded, not understanding her excitement. "That is my birthday as well!"<br /> As it turns out, we have the exact same birthday, just ten years exactly apart. In a country of over one billion, and in a city of around 17 million, I just happened to be randomly selected to live with someone also born on the 17th of July. A coincidence if I may say so myself!

Birthday coincidence - sort of

16 years ago I went on a Project Management course in Bournemouth. On the first evening, as soon as everyone had arrived, we all had dinner together in the hotel's restaurant. About halfway the meal there was a a tap on my shoulder and I turned to face two of my new course colleagues. "Excuse me," one of them said, "I hope you don't mind me asking a rather odd question, but when is your birthday?" I had a flash of insight - there were about 20 of us on the course and I just instinctively knew that my questioner had been telling his dinner partner that in a group of 23 people there is a fifty-fifty chance of two people sharing a birthday. As it happened, it was my birthday that day, and I said as much. "Oh, many happy returns," he exclaimed, putting out his hand to shake mine, "me too!"

Aircraft Engine Failure

During May 1993 I travelled on BA flights from Heathrow to Miami, USA and a couple of weeks later from Heathrow to St Petersburg, Russia. BOTH flights experienced engine failure and in both cases we returned to Heathrow, circled for some time to dump excess fuel and then descended for full emergency landings! In the case of the Miami flight the engine failure occurred near Shannon, Ireland, whilst the St Petersburg engine failure occurred close to Amsterdam. In the case of the 2nd flight from Heathrow to St Petersburg, Russia I asked the flight stewardess whether such engine failures were common and she informed me that this was the 1st such failure in her long flying career, and yet I had 2 "back-to-back" engine failures in the same month! David

Car Mileometer - All The Eights

On 8th August 2008 I drove my car and when I returned home and parked on the driveway I was amazed to see the mileometer read 88,888! It is very strange that the 5 eights appeared when I had parked the car as I may not have noticed it had it happened whilst driving. I have a photo of the mileometer still on my camera which has the date of the event on the image.

friends meet in Boston years later

My brother comes from, and lives in, Ireland. He grew up with someone who eventually had to immigrate to USA. Many years later my brother had to go to the US and in the course of his stay he decided to take a day off to sight-see. He picked Boston and set off. In Boston he had to wait in a group of other people to cross the road. As he stood there he thought he recognised the back of the head of someone in front of him. He reached forward through the crowd to tap the person on the shoulder. It was his friend, who lived in a totally different town, but who had also been taken with the urge to visit Boston for the day!

Coworkers in Boston born same day/year in same hospital in Ohio

I came to work at a Statistical Analysis Center at a Medical School in Boston several years ago. I am originally from Toledo Ohio (a city of about 300,000 some 800 miles away from Boston) I heard that one of my co-workers was also from Toledo. When we met we discovered that we born in the same year. At some later point, we discovered that we had the same birthday. For her next birthday, I decided to give her a unique birthday card containing a copy of the newspaper birth announcements for the day of our mutual birth. When I received it from my family in Ohio, I found that my coworker and I were born in the same hospital (there were perhaps half a dozen in Toledo itself at that time, maybe twice that number in the metropolitan area).

Globetrotting teddy bears

Last March, I received a phone call from a friend living near Hull. He asked if my young daughter would be prepared to receive a teddy bear that was travelling the world as part of a school project. He had received it from a friend in Holland. The school was in Illinois USA and the young children had been instructed to each dispatch a teddy bear to anyone in the world that they knew, with the instructions that it should then be posted on to another friend anywhere in the world and then another friend and so on. Instructions included with the globetrotting bear said that it should be returned to the school address by the end of October. I said yes and the bear duly arrived a few days later. Because it was an interesting project my daughter took the bear to school to show her teacher and classmates. Sitting next to her, her schoolfriend said that she had also received a bear that had originated from the same Illinois school. It had come via friends in South Africa and she brought it in the next day.

Pin code coincidence

Opened new bank account, they sent me a card and four digit pin. The pin was my work extension telephone number minus one! Changed pin to something a bit more secure, i.e. not related to a number I commonly use or associate with. Interesting question, how random (secure?) are our given vs chosen pin codes and is there a best strategy for choosing one? Maybe I should have stuck with the one supplied?

Golden Anniversary Yolks

In May 2007 my parents came to Cambridge to celebrate their golden wedding with us. For this very special occasion I decided to bake a rather lavish Austrian cake (my mother was Austrian and my parents got married there). The recipe required 12 eggs (plus other ingredients including hazel nuts, raspberries, lots of cream). I went to the supermarket (Tesco) and bought a packet of twelve nice large, free-range eggs. When I came to make the cake, the first egg had two yolks. I was a little surprised. The second egg had two also. How odd! By the time I got to egg number twelve and it had two yolks as well, I was gobsmacked. Before that, I had only ever seen one, maybe two, such eggs in my whole life. The cake was a great success, but what stuck with me was how lovely it was to have all those golden pairs of yolks for that particular cake. For me, the timing was the real coincidence. Kate

Hitchhiking to Louisville from Toronto

Back in 1970 my girlfriend and I decided to visit a friend in Louisville Kentucky. We left Toronto and got our first ride to the outskirts of Hamilton (about one hour) By this time it was getting dark and we weren't sure what to do when a car pulled up. We got in and amazingly it was another friend who I hadn't seen for two years. The huge coincidence was he was driving to Louisville to visit our friend too. This was an incredible stroke of luck for us and we were able to travel in comfort for the rest of the long journey plus catch up on what happened for the past two years.

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