Statistics and Sweepstakes

Posted By Pamela on Sep 30, 2007 | 10 comments

Today I was bad to myself and stopped by McDonald’s on the way into campus and got a soda and fries. (If I’m going to go to campus on a Saturday I feel ok being bad to myself). On the bag they handed me their was a code and a website and an invitation to participate in a sweepstakes. My first thought was, “Wow, they’re working hard not to give away money.” My second thought was, “I miss the monopoly game.”

Here is why. With the monopoly game I had a 1 in (something like) 6 chance of instantly winning something. This means that if I get a soda and fries 3 times, I’ll probably get 1 free something. This will actually work in getting me to go to McDonald’s over Wendy’s or the Quikie Mart when I want a soda and a munchie. For McDonald’s, this means they give away more free stuff, but it also means the get more business. This is a lose-win scenerio.

With the monopoly game, getting the big ticket items is harder – it requires folks to collect a series of pieces that often distributed in a way that makes it hard for one person to get all the pieces, and they have some pieces (that for obvious reasons) only exist in small numbers (small being defined as like 5, in some cases). In some cases, people will pieces that are rare, and lose them or throw them out – thus McD’s doesn’t have to give out the winnings. It is possible, some years they won’t have to give out any big ticket prizes (I don’t think this has happened).

By putting the prize info on a bag and requiring folks to log in, they are making it even more likely that they won’t have to give out all the prizes. My bag when straight to the trash. Some folks, like the homeless folks who really could use the free fries, probably aren’t going to type their numbers in at the local library’s internet cafe. I’m not sure McD’s will get the same surge in sales (not my field), but they will definitely get more info on who’s playing, and that has it’s own value.

Sweepstakes and lotteries are really a tax on the mathematically illiterate. Sure, I’ll randomly buy tickets when the amount one can potentially win gets sufficiently large,  but I plan to throw that money away.

Think of it this way. If galaxies typically produce 1 supernova a per hundred years, I need to watch at least 100 galaxies every day for 1 year to have a high probability of catching 1 SN on it’s first day.

Now, for your typical 6 numbers with 49 options lottery, there is 1 chance in 13,983,816 that any particular combination of will come out of the machine. This means that you have to play 13,983,816 times to have a high probability of winning. Or, if you are part of a ticket pool, you would have to buy 100 tickets a week for 2,689 years to have a high probability of winning. Now, you could spoil the statistics and be the fluck who tries once and wins, but… The odds aren’t in your favor 🙂

The odds are always in favor of the house, and whenever there is a sweepstakes that requires you to collect pieces, be present for the drawing (no replacement drawings made), or something other than an instant win, the person putting forward the money you might win is hoping you won’t follow through.

McDonalds: I like your fries, but your latest sweepstakes just gives me a statistical headache.


  1. I’ve thought about that too, just after learning expectations in math.

  2. The average American man has a higher probability of getting rich by marrying Elizabeth Taylor than by winning the lottery.

  3. “I need to watch at least 100 galaxies every day for 1 year to have a high probability of catching 1 SN on it’s first day.”

    Double that if you’re using visible light 🙂 unless it’s a really *really* big SN …

  4. Add to your list of companies hoping you won’t collect the rebate scamers. Instead of discounting in the store you have to send in for your money. Even better are the phone companies that make you have their service for six months before you can send in your rebate forms. Now how many people are going to remember after six month. SCAM, SCAM, SCAM!

  5. Hi Pam,
    I used to listen to astronomy cast just for something to listen to while I worked. Until I simply got fed up with you thinking you know everything especially when you were wrong on so many points you speak about. You are so quick to say there is no way or it could never happen that I laugh inside but cry aloud for your fans who think you know so much and get misinformed because most of them are amateurs at best. For example there are multiple variables that could cause apophis or any NEO to deviate from its projected trajectory. Another example is you say that all nebula are not dense enough to carry a sound wave. It is obvious that some nebulas are very dense (uh, that is how stars are born.). These are just a couple examples of how dumb you sound especially when you think you actually know for a fact. And if it was not for the dumb guy on your pod cast you would sound even dumber than you already do. So lets see here; you don’t think for yourself or out of the box at all, you regurgitate information you read, and you sorry to say have a lot to learn especially for an academic professor.

  6. Dear YouAreAJoke,

    Thank you for not signing your name. It protects you from letting me judge you within your field of expertise.

    I would challenge you to identify the objects that can cause Apophis to deviate from it’s known orbital trajectory. People have done these models using all objects of sufficient mass to cause significant deviations, and we’re safe. Period. No, I didn’t do these studies myself, but the thing about science is everyone doesn’t have to repeat everyone else’s calculations. I also challenge you to find a nebulae – not a proto star (they are different) that carries sound waves well enough to carry sound the human ear can hear.

    You challenge things as sounding dumb because they don’t meet your preconceived understanding. Where do these preconceptions come from? What research are you basing your doubt on?

    You’re right, so far I haven’t talked about my own research in Astronomy Cast. That’s not the point of the show however. Have you ever heard Neil Tyson or Phil Plait discuss their research? We each study one small area, but we share information from all over the universe.

    You are welcome to try and produce your own podcast and do better. Astronomy Cast doesn’t define the end all – be all of podcasts. It defines what we do, and it makes us happy. If you don’t like it, don’t listen. Name calling on my blog is frankly rude.


  7. Pamela, please, please please do NOT take to heart any of the venom spewed by “YouAreAJoke” your podcast and blog are enjoyed by so many of us that never get the time to say how wonderful we think they are and what a great job we think you are doing. Keep up the good work and ignore those that hide under their rocks and throw stones and others.

  8. Pamela, I agree – ignore idiots like YouAreAJoke. I suspect he believes tinfoil is fashionable. Your blog and podcast are great, and I hope they continue!

  9. I never got the impression that you believed that you know it all. It sounds like you just hit a nerve with someone who can’t rationally and scientifically argue a point. As you stated, I would like to see this person present their theory so that it can be discussed. I’m sure if I did’t agree with something like how the universe isn’t expanding into anything I could find other sources and bring them up for open and enlightened discussion. I appreciate the time that you and Fraser spend on puting together the show.

  10. Pamela, it is a credit to you that you bothered responding at all to that clown, and even more so that you did so in such a measured, calm and controlled manner. I’m sure I couldn’t have managed that.

    I suspect it is safe to assume the vast majority of your AstronomyCast listeners understand that your show doesn’t purport to be the ‘be-all and end-all’ (as you said), of current scientific understanding, but rather a glimpse into a world too complex for many enthusiasts to understand without some ‘dumbing down’ by those who do.

    There are always critics – at least most have the professional courtesy to not criticize from the shadows.

    Keep on blogging Pamela – your reasons for doing so are spot on.

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