# Probability question

#### mixunitz

Hi guys I need some help with this probability question

100 people are asked whether a baseball team will win or lose a game

80 people say they will win, 20 people say they will lose

Does this mean the crowd of 100 is saying that the team has a probability of 80 percent winning and 20 percent losing?

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#### romsek

Math Team
well...

As you learn more about probability you'll learn that's not exactly the way you want to phrase it but for now it's close enough.

I would phrase it as "based on a sample of 100 people the estimate of the probability of the team winning is 80%"

Thanks rom

#### DarnItJimImAnEngineer

If this is a poorly-written maths textbook, then that is probably the answer.

In the real world, I would say that 80 % of the people polled predicted the team would win, and that any statements along the lines of what was said above (predicting the probability of the team winning) are severely misleading. In fact, I would argue calling it anything better than an, "(educated) guess," is either ignorant or deceptive.

Think of it this way. Some people will be fans of the team and will disproportionately predict a win. Some people will be fans of the opposing team and disproportionately predict a loss. Some people will factor in past performance, knowledge of the players, etc.. Of course, how well they do this, and how well that information corresponds to the odds of winning, may vary.

Even using the, "Is the crowd saying the odds are 80 %," approach, it's pretty iffy. Maybe the 20 who predicted a loss thought they could win, but the odds were slightly against them, while the 80 who predicted a win thought it was a slam dunk (ha-ha). Overall popular opinion would put the odds higher than 80 %, but by taking the electoral college approach to counting, you have skewed the odds.
[/rant]

#### mixunitz

Thanks Jim

So your saying a better way of saying it is 80 percent of the crowd polled predict the team to win?

But wouldn't this work out to 80 percent probability?
Similar to say a horse race, where there is a pool of money and the odds/probabilitys are determined by who bets on which horse?

#### DarnItJimImAnEngineer

So your saying a better way of saying it is 80 percent of the crowd polled predict the team to win?
Yes.

But wouldn't this work out to 80 percent probability?
Similar to say a horse race, where there is a pool of money and the odds/probabilitys are determined by who bets on which horse?
Yes, you could consider this odds for betting, if that's how they calculate it (neither a bookie nor a gambler here). My point was that claiming this number is a probability of winning depends on some strong correlation between crowd predictions and game outcomes.

Thanks Jim