Bike Forums > Foo > Statistics question
 Register All Albums Elite Membership Forum Rules Calendar Search Today's Posts Mark Forums Read

 Foo Off-Topic chit chat with no general subject.

 11-19-07, 10:49 PM #1 timmyquest Banned. Thread Starter     Join Date: May 2005 Location: Woodstock Bikes: Posts: 5,761 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Statistics question So i went out with my cousin and some friends her friends...to the church, for some bingo (yeah baby). Anyways, after a game where we didn't win (again), one of her friends said "It was probably one of those people with a ton of cards." This lead to a discussion on statistics to which i claimed that your odds were the same regardless of how many cards you have. She wouldn't have any of it. I don't think she's entirely wrong, and i don't think I'm entirely wrong. It's been a few years since I've taken a stats class and none of the statistics i deal with for my schoolwork is related to odds/probability etc. So, if you have one dice you have a 1/6 chance of rolling a six. If you have two dice, each dice still has a 1/6 chance of rolling a dice. So, your chance is still 1/6 of rolling a 6 right? Or is it 2/12...which is the same thing. Right, i just figured it out didn't I (why didn't i bring that fact up earlier).
11-19-07, 10:53 PM   #2
Tom Stormcrowe
Out fishing with Annie on his lap, a cigar in one hand and a ginger ale in the other, watching the sunset.

Join Date: Mar 2006
Location: South Florida
Bikes: Techna Wheelchair and a Sun EZ 3 Recumbent Trike
Posts: 16,128
Mentioned: 1 Post(s)
Quoted: 0 Post(s)
Each dice individually has a 1:6, but to roll simultaneous 6's it'd be 1²:6² or 1:36

Quote:
 Originally Posted by timmyquest So i went out with my cousin and some friends her friends...to the church, for some bingo (yeah baby). Anyways, after a game where we didn't win (again), one of her friends said "It was probably one of those people with a ton of cards." This lead to a discussion on statistics to which i claimed that your odds were the same regardless of how many cards you have. She wouldn't have any of it. I don't think she's entirely wrong, and i don't think I'm entirely wrong. It's been a few years since I've taken a stats class and none of the statistics i deal with for my schoolwork is related to odds/probability etc. So, if you have one dice you have a 1/6 chance of rolling a six. If you have two dice, each dice still has a 1/6 chance of rolling a dice. So, your chance is still 1/6 of rolling a 6 right? Or is it 2/12...which is the same thing. Right, i just figured it out didn't I (why didn't i bring that fact up earlier).
__________________
. “He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you.”- Fredrick Nietzsche

"We can judge the heart of a man by his treatment of animals." - Immanuel Kant

11-19-07, 10:55 PM   #3
KingTermite
On my TARDIScycle!

Join Date: Jun 2005
Location: Eastside Seattlite Termite Mound
Bikes: Trek 520, Trek Navigator 300, Peugeot Versailles PE10DE
Posts: 3,925
Mentioned: 0 Post(s)
Quoted: 5 Post(s)
Quote:
 Originally Posted by timmyquest So, if you have one dice you have a 1/6 chance of rolling a six. If you have two dice, each dice still has a 1/6 chance of rolling a dice. So, your chance is still 1/6 of rolling a 6 right? Or is it 2/12...which is the same thing. Right, i just figured it out didn't I (why didn't i bring that fact up earlier).
I believe it would be 1/6 + 1/6 or 2/6 = 1/3.

More cards equals N number of more chances to get the number called. Now there are more factors involved with a bingo card...there are only so many possible numbers in each column, and there is a possibility of repeat numbers, but still your chances are definitely going to be increased with more bingo cards.
__________________
Quote:
 Originally Posted by coffeecake - it's pretty well established that Hitler was an *******.

11-19-07, 10:56 PM   #4
KingTermite
On my TARDIScycle!

Join Date: Jun 2005
Location: Eastside Seattlite Termite Mound
Bikes: Trek 520, Trek Navigator 300, Peugeot Versailles PE10DE
Posts: 3,925
Mentioned: 0 Post(s)
Quoted: 5 Post(s)
Quote:
 Originally Posted by Tom Stormcrowe Each dice individually has a 1:6, but to roll simultaneous 6's it'd be 1²:6² or 1:36
I don't think he referred to simultaneous...I think he meant the chance of rolling one 6 with 2 rolls (e.g. 2 chances).
__________________
Quote:
 Originally Posted by coffeecake - it's pretty well established that Hitler was an *******.

11-19-07, 10:57 PM   #5
timmyquest
Banned.

Join Date: May 2005
Location: Woodstock
Bikes:
Posts: 5,761
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by Tom Stormcrowe Each dice individually has a 1:6, but to roll simultaneous 6's it'd be 1²:6² or 1:36 Add a power with each dice added, 3D6=1:6³ and so on
If we are to relate it to BINGO, i don't think you'd apply this rule because you don't need a bingo on each card, just one card.

 11-19-07, 10:57 PM #6 jschen riding once again     Join Date: Oct 2005 Location: San Diego, CA Bikes: '06 Cervelo R3, '05 Specialized Allez Posts: 7,359 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Argh... timmyquest, of course the number of attempts matters. Let's take a simple example to convince ourselves of this. If you flip a fair coin, you have a 50% chance of getting heads. If you flip 100 coins, you are virtually assured of getting at least one coin coming up heads. Right? My next post will analyze your two dice issue. You can generalize from there. __________________ If you notice this notice then you will notice that this notice is not worth noticing. Last edited by jschen; 11-20-07 at 12:39 AM.
 11-19-07, 11:00 PM #7 jschen riding once again     Join Date: Oct 2005 Location: San Diego, CA Bikes: '06 Cervelo R3, '05 Specialized Allez Posts: 7,359 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Your chances with one die are as following: 1/6 you roll a 6 5/6 you roll not a 6 Since the results on the two dice are independent events, you can simply multiply probabilities: 5/6 * 5/6 = 25/36 you roll not a 6 on both dice 1/6 * 5/6 = 5/36 you roll a 6 on the first die but not the second 5/6 * 1/6 = 5/36 you roll a 6 on the second die but not the first 1/6 * 1/6 = 1/36 you roll a 6 on both dice So 11/36 chance you get at least one 6. Which should be clear without analyzing the entire situation by simply asking how many ways you don't get any 6's. Next post: How this applies to a classic math problem involving birthdays... __________________ If you notice this notice then you will notice that this notice is not worth noticing.
 11-19-07, 11:10 PM #8 jschen riding once again     Join Date: Oct 2005 Location: San Diego, CA Bikes: '06 Cervelo R3, '05 Specialized Allez Posts: 7,359 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Suppose you ask what the probability is that in a group of 30 people picked at random, at least two share a birthday (not counting the year). And for ease of math, assume no one born on Feb 29, though the results don't change significantly (and it's not hard to calculate). You can build a complex equation, but let's just analyze the approach using common sense. With one person, obviously there can't be a shared birthday. Probability 1 that there is no shared birthday. With two people, there is a 364/365 chance the second person doesn't share the first person's birthday. Suppose that's the case. (Because if it isn't the case, you can stop checking the others' birthdays.) Now two dates out of 365 are already claimed, and there is a 363/365 chance the third person doesn't share a birthday with either the first person or the second person. So on and so forth... So for the Nth person you add to the group of people, there is a (366-N)/365 chance that if you started with no shared birthdays, after adding that person, you still don't have a shared birthday. So for N people, you have (365/365) * (364/365) * ... * (366-N)/365 chance, simplifying to 365!/(365-N)!/365^N chance, of having no shared birthdays. So you have 1 - [365!/(365-N)!/365^N] chance you have a shared birthday. For N = 30, there's a ~70% chance of a shared birthday. __________________ If you notice this notice then you will notice that this notice is not worth noticing.
 11-19-07, 11:11 PM #9 jschen riding once again     Join Date: Oct 2005 Location: San Diego, CA Bikes: '06 Cervelo R3, '05 Specialized Allez Posts: 7,359 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Hope that helps. Let me know if you have any questions. __________________ If you notice this notice then you will notice that this notice is not worth noticing.
11-19-07, 11:20 PM   #10
jschen
riding once again

Join Date: Oct 2005
Location: San Diego, CA
Bikes: '06 Cervelo R3, '05 Specialized Allez
Posts: 7,359
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by KingTermite I believe it would be 1/6 + 1/6 or 2/6 = 1/3.
This is a good approximation if the odds of a single event are very low and the number of trials is very low. (How low depends on how good an approximation you want.) For the case of two dice, 1/3 = 12/36 is a pretty good back of the envelope estimate for the real answer of 11/36.

When those criteria don't hold, you'll overestimate your chances. If you flip a fair coin twice, your chances of getting at least one heads is 3/4. But this estimate predicts probability 1. The reason you overestimate is easily analyzed in this model case. You're counting the times you flip two heads as two successful cases.

Without getting into a lot of math (I have to get back to writing for work, and besides, I don't want to bore Foosters more than I already have) this is why it is a good approximation for low probability events. You aren't likely to get more than one hit (if you get one at all), so you can basically just multiply the probability for a single attempt by the number of attempts. But if there is a significant possibility of multiple hits, then this approximation becomes screwy.

Okay, as much fun as this is compared to writing for work, I should get back to work.
__________________
If you notice this notice then you will notice that this notice is not worth noticing.

 11-19-07, 11:40 PM #11 mezza Senior Member     Join Date: Aug 2006 Location: On the intramaweb thing. Bikes: Steel geared. Steel Fix. Posts: 1,016 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) When I studied marketing I had a statistics exam. I rushed through the paper answering all the questions I knew instantly. I rushed through a second time answering all the questions I'd have to do a maximum of 20 seconds working out on. I then worked out that I had pretty much got the pass mark already and all I had to do was guess the rest, so I did. I aced a 3 hour exam in 20 minutes
11-20-07, 12:06 PM   #12
deraltekluge
Senior Member

Join Date: Sep 2006
Bikes: Kona Cinder Cone, Sun EZ-3 AX
Posts: 1,195
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by jschen If you flip a fair coin, you have a 50% chance of getting heads. If you flip 100 coins, you are virtually assured of getting at least one coin coming up heads. Right?
It depends on who's doing the flipping. There are people who can flip a coin and get what they want every time.

And of course having more cards in bingo improves your chances of winning, just as playing more sets of numbers in a lottery improves your chances there.

Think of it this way: Suppose that there are 100 cards being played. Divide them into two sets of 50. There is an equal chance of the winner being in each set. Now, suppose one player has 50 cards, and the other cards are distributed among 50 other players. The player with 50 cards will win half the time, and each of the 1-card players will win 1/100 of the time.

 11-20-07, 12:09 PM #13 deraltekluge Senior Member     Join Date: Sep 2006 Bikes: Kona Cinder Cone, Sun EZ-3 AX Posts: 1,195 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Some terminology: If you have two or more, they are dice. If you have just one, it's a die...remember the phrase, "The die is cast."
11-20-07, 12:18 PM   #14
timmyquest
Banned.

Join Date: May 2005
Location: Woodstock
Bikes:
Posts: 5,761
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by deraltekluge And of course having more cards in bingo improves your chances of winning, just as playing more sets of numbers in a lottery improves your chances there.

This is actually where my confusion came from. The odds in most lotto games are so astronomical that buying a few more tickets does not significantly improve your odds.

1 in 30,000,000 is about the same as 10 in 30,000,000

11-20-07, 12:22 PM   #15
CliftonGK1
Senior Member

Join Date: Jul 2006
Location: Columbus, OH
Bikes: '08 Surly Cross-Check, 2011 Redline Conquest Pro, 2012 Spesh FSR Comp EVO, 2015 Trek Domane 6.2 disc
Posts: 11,378
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
Quote:
 Originally Posted by deraltekluge Some terminology: If you have two or more, they are dice. If you have just one, it's a die...remember the phrase, "The die is cast."
What if they were press-form molded, rather than cast?
__________________
"I feel like my world was classier before I found cyclocross."
- Mandi M.

11-20-07, 12:25 PM   #16
squegeeboo
******

Join Date: Dec 2006
Location: Rochester, NY
Bikes: Specalized Tri-Cross
Posts: 951
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
Quote:
 Originally Posted by deraltekluge Some terminology: If you have two or more, they are dice. If you have just one, it's a die...remember the phrase, "The die is cast."
I always thought the plural of thingen was always en. so it would be dien, or perhaps dicen. Just like micen or goosen.
__________________
In the words of Einstein
"And now I think I'll take a bath"

 11-20-07, 12:35 PM #17 zbicyclist Dilettante     Join Date: Jan 2002 Location: Chicago Bikes: Posts: 66 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) [QUOTE=deraltekluge;5666299] And of course having more cards in bingo improves your chances of winning, just as playing more sets of numbers in a lottery improves your chances there. [QUOTE] But playing more cards, or playing more sets of lottery numbers, also increases the amount you lose. Since both are negative sum games, your expected winnings are higher in both cases if you don't play at all. __________________ -- Oldest bike: 1970 Schwinn Twinn Tanndem
11-20-07, 12:36 PM   #18
deraltekluge
Senior Member

Join Date: Sep 2006
Bikes: Kona Cinder Cone, Sun EZ-3 AX
Posts: 1,195
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by timmyquest This is actually where my confusion came from. The odds in most lotto games are so astronomical that buying a few more tickets does not significantly improve your odds. 1 in 30,000,000 is about the same as 10 in 30,000,000
Roughly speaking, you have twice the chances of winning with two tickets as you do with one, and ten times the chances with ten tickets.

Take it to an extreme. Suppose the odds are 14 million to one (that's about what it is for picking 6 out of 49). Suppose you buy 14 million lottery tickets, all different...you're certain to win.

Some people actually tried to do that in a lottery where the pay-off had grown so much that it was much greater than the cost of the tickets. The didn't succeed in buying all those tickets...they ran out of time...but they won anyway. The state tried to refuse to pay, but the last I heard was that a court had awarded them the money.

 11-20-07, 12:37 PM #19 ModoVincere Riding Heaven's Highways on the grand tour     Join Date: Aug 2006 Bikes: Posts: 1,675 Mentioned: 1 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) what's it matter anyway....if its a gambling game, the odds are gonna be stacked against you. You know the old saying..."What ever you bring to vegas, stays in vegas" __________________ 1 bronze, 0 silver, 1 gold
11-20-07, 12:39 PM   #20
deraltekluge
Senior Member

Join Date: Sep 2006
Bikes: Kona Cinder Cone, Sun EZ-3 AX
Posts: 1,195
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by zbicyclist But playing more cards, or playing more sets of lottery numbers, also increases the amount you lose. Since both are negative sum games, your expected winnings are higher in both cases if you don't play at all.
But that's no fun.

11-20-07, 12:41 PM   #21
squegeeboo
******

Join Date: Dec 2006
Location: Rochester, NY
Bikes: Specalized Tri-Cross
Posts: 951
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
Quote:
 Originally Posted by deraltekluge Roughly speaking, you have twice the chances of winning with two tickets as you do with one, and ten times the chances with ten tickets. Take it to an extreme. Suppose the odds are 14 million to one (that's about what it is for picking 6 out of 49). Suppose you buy 14 million lottery tickets, all different...you're certain to win. Some people actually tried to do that in a lottery where the pay-off had grown so much that it was much greater than the cost of the tickets. The didn't succeed in buying all those tickets...they ran out of time...but they won anyway. The state tried to refuse to pay, but the last I heard was that a court had awarded them the money.
Last time I heard of someone doing something like that, there ended up being 3-4 winners, so the one guy who bought several mill in tickets ended up in the red a few hundred thousand.
__________________
In the words of Einstein
"And now I think I'll take a bath"

11-20-07, 01:05 PM   #22
timmyquest
Banned.

Join Date: May 2005
Location: Woodstock
Bikes:
Posts: 5,761
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by deraltekluge Roughly speaking, you have twice the chances of winning with two tickets as you do with one, and ten times the chances with ten tickets. Take it to an extreme. Suppose the odds are 14 million to one (that's about what it is for picking 6 out of 49). Suppose you buy 14 million lottery tickets, all different...you're certain to win. Some people actually tried to do that in a lottery where the pay-off had grown so much that it was much greater than the cost of the tickets. The didn't succeed in buying all those tickets...they ran out of time...but they won anyway. The state tried to refuse to pay, but the last I heard was that a court had awarded them the money.
twice of nothing is still nothing

Statistically insignificant increases in your odds are essentially nothing. So if your odds are essentially nothing, and you increase them by essentially nothing, then again you are still left with nothing. I'm not saying that applies with BINGO, i don't know the odds there, but lets just think of this:

I was at a table with 8 people and 10 cards all together.

That would cost \$90 to buy those cards.

No one at my table won.

...seems as though the increase in odds wasn't very important was it.

11-20-07, 01:25 PM   #23
jschen
riding once again

Join Date: Oct 2005
Location: San Diego, CA
Bikes: '06 Cervelo R3, '05 Specialized Allez
Posts: 7,359
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by timmyquest twice of nothing is still nothing
True, but it's still twice as much. Also, for the lottery players in aggregate (or put another way, for the person running the lottery), it does matter since the sample size is so huge. Whether having more chances increases odds is something mathematically quantifiable. It most definitely does. Whether or not that amount matters is a matter of perspective.

Quote:
 ...seems as though the increase in odds wasn't very important was it.
Statistics doesn't predict with accuracy what will happen any one time in a small sample size. It predicts averaged behavior over very large numbers. Your "experiment" didn't involve very large numbers.
__________________
If you notice this notice then you will notice that this notice is not worth noticing.

11-20-07, 01:44 PM   #24
eubi
No Rocket Surgeon

Join Date: Jan 2005
Location: Corona and S. El Monte, CA
Bikes: Cannondale D600, Dahon Speed T7
Posts: 1,648
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
 Originally Posted by jschen . If you flip a fair coin, you have a 50% chance of getting heads.
Generally true, but twice in my life, with God as my witness, I have flipped a coin that landed on its edge.

So it's slightly less than 50%.

How many sides does a coin have? Three!
__________________
Fewer Cars, more handlebars!

 11-20-07, 01:55 PM #25 jschen riding once again     Join Date: Oct 2005 Location: San Diego, CA Bikes: '06 Cervelo R3, '05 Specialized Allez Posts: 7,359 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Fair enough. __________________ If you notice this notice then you will notice that this notice is not worth noticing.