National Lottery

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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.

Submitted by david on Wed, 07/11/2007 - 3:59pm

LotteryThe UK National Lottery began on 19th November 1994 and there had been 1240 draws up to 20th October 2007. The jackpot prize is won by choosing in advance the 6 numbers that will be drawn from a set of balls numbered from 1 to 49. We can use the history of the lottery to illustrate many aspects of the theory of probability: how each draw is individually unpredictable, and yet the overall history shows predictable patterns; how a `league table' of numbers can be created that appears to show some numbers are preferentially drawn, and yet the table is completely spurious; how to test whether the balls are truly being drawn at random; how extremely unlikely events will occur if you wait long enough, and so on.

The animation below shows how often each of the 49 numbers came up in the first 1240 draws. Use the playback controls below the animation to restart, pause, or fast forward the draws.
You need to install the Adobe Flash Player to see the animation.

Click to enlarge the animation

Starting from 1994, note how the 'leader' changes, until one number seems to gain a substantial lead.

If you click on 'Show histogram', you can create the current distribution showing how often each of the 49 numbers has come up. Press 'Start dropping' to see how that histogram arises. The distribution seems quite spread out, with some numbers appearing much more often than others, but in fact this apparent spread should be purely due to chance. Lottery Expectations considers what sort of distribution of total appearances of each number we would expect when lottery balls are chosen at random.

What about the gaps between numbers?

Using the animation above, work backwards from October 2007 and see how long you have to wait until the last number appears. Do you think this is surprising? We can use probability theory and simulations to explore how long we have to wait for a number to come up.

The animation below shows the gap between each time a number comes up.

You need to install the Adobe Flash Player to see the animation.

Click to enlarge the animation

Can you see the longest gap that has occurred? Look carefully from the start of 2000. Do you think this is surprising? Lottery Expectations considers what sort of gaps between numbers we would expect when lottery balls are chosen at random.

Further reading and links

This is based on an idea by Fenton on considering the lottery results as a league table.

A spreadsheet with the full lottery history can be downloaded from the main UK National lottery site

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Comments

Jake Anderson (not verified)

Thu, 01/12/2011 - 11:17am

Thanks for sharing! This was informative. i enjoy my playing lottery as i am able to give back to the society at health lottery numbers. Your animation was useful to me . Thanks!

dude (not verified)

Fri, 02/12/2011 - 1:52am

Hello, so i understand the uk national lottery has 2 drawings - on at wednesday and the other takes place on saturday. From my point of view it would be interesting to see how many first prizes (only) have been won on saturday and how many on wednesday. Do You think You could make such a histogram? Thank You!

hombreguapo

Sat, 20/10/2012 - 12:45pm

Interesting program on BBC 4 this week with the Professors musings. I'm interested in how Random the Lottery numbers are or aren't. On paper, 123456 or any consecutive numbers are just as likely as so-called Random ones to pop up. How can that be? As there are only what? 44 (UK LOTTO) different combinations of consecutive numbers that can come up compared to nearly 14 million other combinations. Of all the lotteries in the world, has there ever been a randomly selected consecutive group of numbers picked? I find that if I pick the numbers myself and look at the draw history numbers I seem to win more than if I choose to do a lucky dip at the store. Anyone else say different?