# odds/probability

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#### piotr1980

##### Senior Member
Hello,

Does a word ''odds'' mean the same as probability?
If so, can we say

''Your odds to be hired in this company are minor''

Many thanks
Piotr

• #### mjscott

##### Senior Member
You usually say "odds of".

minor sounds awkward--unnatural to me.

I would say,
"Your odds of being hired in this company are minimal/nil/next to non-existent."

When you use probability, I would say,
"The probability of you being hired in this company are minimal/nil/next to non-existent."

#### Jacobian

##### Member
If you're trying to decide whether to use "odds of" or whether to use "probability of":

There is a mathematical difference betweens odds and probability. In your case, and in most cases, you should use "probability" if you want to be mathematically correct:
''The probability of being hired in this company is negligible.''

Here is the difference:

Mathematically:
If there is a white ball and a black ball in a box, and you choose one of them without looking, you can say this:

"The probability is 1/2 that I will choose the black ball."
"The odds are 1:1 that I will choose the black ball."

Both are correct!

But it's wrong to say:
"The odds are 1/2 that I will choose the black ball."
...what you really mean is "probability"

All the same, most people don't know the difference. Because of that, you honestly do hear "odds" used quite often in English:
"Your odds of being hired in this company are negligible."

Even though it's probably better to use probability.

#### tomu

##### Member
I'm not a mathematician, so I don't know if the terms mentioned by Jacobian are used that way universally, but in everyday speech there is a transatlantic difference in the way we use the word "odds" when it comes to betting...

In the UK:

1:1 = evens (1/1)
2:1 = two to one (2/1)
1:2 = two to one on (1/2)
5:4 = five to four (5/4)
1:3 = three to one on (1/3)
etc,

This is the system that people are familiar with here and if you said you were backing a horse whose odds were "5 to 1" then everyone would know what you meant (i.e. if your horse wins then you win five times your stake plus your stake back)... using the decimal betting system that would be 6.0.

In the USA (and I think in Australia also) they use different systems so I don't know how the "man in the street" there would describe the different odds mentioned above.

#### Jacobian

##### Member
Right, everything that tomu said is correct. They are all odds!

In contrast, a probability is always a fraction between 0 and 1.

Even when the odds are presented as a fraction, keep in mind that it just a comparison between two numbers, like 1:1, and not a true fraction.

If you see the odds written as "2:1" or "2/1" it is only a side-by-side comparison between the two possible outcomes -- not a number. The probability is the only one that is a number, and it is always between 0 and 1. In this case: "2:1" is the same as the fraction "1/3"

Here is the formula for converting:
"m:n" = n/(m+n)

This is universal.

But many people across the world don't know the difference (except for tomu: his post on odds is right.)

#### okey-dokey

##### Senior Member
Hello,

Does a word ''odds'' mean the same as probability?
If so, can we say

''Your odds to be hired in this company are minor''

Many thanks
Piotr
It is not usual to use odds in the way you have written. The usual ways:

"The odds of you being hired are low / high."
"The odds of you being hired are bad / good."
"The odds of you being hired are against you."
"The odds of you being hired are in your favour."
"The odds are that you will / will not be hired."

Notice that it is the odds and not your odds.

Can you replace odds by probability? Yes and no. First, note that probability is singular. Secondly, there are certain collocations.

"The probability of you being hired is low / high."
? "The probability of you being hired is bad / good."
* "The probability of you being hired is against you."
? "The probability of you being hired is in your favour."
"The probability is that you will / will not be hired."

? = acceptable but not a usual collocation.
* = not acceptable.

However, you can say, "There is a good probability of you being hired." (But, not bad probability).

If you move into the world of statistics and epidemiology, then odds (as in odds ratio) and probability have precise defintions.

#### Lucky_15

##### Member
Hello,
I have a small question.
if you said you were backing a horse whose odds were "5 to 1" then everyone would know what you meant (i.e. if your horse wins then you win five times your stake plus your stake back)... using the decimal betting system that would be 6.0.
Following the above logic, the odds of 10 to 1 will give 11 if win.
But in the Oxford OALD, they define: odds of 10 to 1 = 10 times the amount of money that has been bet by <somebody> will be paid to them if they win.
so which one is incorrect?
Thank you.

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#### pob14

##### Senior Member
10 to 1 = Bet 1 dollar, win \$10 plus your bet back. (The win is \$10, but you also get your wager back. If you didn't get your wager back, you wouldn't be winning \$10, you'd be winning \$9.)

10 for 1 = Bet 1 dollar, win 10 but the other side keeps your original bet. Some Las Vegas casinos used to quote odds this way, in order to give payouts that seemed larger but really weren't. I don't think it's done very much any more.

(This is speaking US: I'm not sure what tomu thinks is the transatlantic difference.)

Also, let me be the first to remind you: "sb" is not an abbreviation which is allowed here, because it is not understood by most native speakers.

#### wandle

##### Senior Member
I would never say 'the odds of' anything, as this can cause the very confusion clearly explained by Jacobian.
It is better to say 'the odds on' or 'the odds against'.

If we say the odds on a horse winning are five to one, this means the probability it will win is 5/6.
If we say the odds against are five to one, we mean the probability of the win is 1/6.

#### Egmont

##### Senior Member
Hi Wandle, just to make sure, the probability is 5/6, not 1/6 right?
No. wandle was right in the original post which you edited in your "quote." If you read that the odds on a horse are 100 to 1, it means that the horse has about a 1% chance of winning.

(Technically, these are not the actual odds of the horse's winning, but the payout that is necessary for bookmakers and race tracks to break even if that horse wins. It is a measure of gambler sentiment, not of the horse's performance. The actual odds of a horse winning are probably impossible to calculate and in any case are not posted. The two figures are closely related, though.)

#### PaulQ

##### Banned
I would never say 'the odds of' anything, as this can cause the very confusion clearly explained by Jacobian.
It is better to say 'the odds on' or 'the odds against'.

If we say the odds on a horse winning are five to one, this means the probability it will win is 5/6.
If we say the odds against are five to one, we mean the probability of the win is 1/6.
The use of odds on and odds against, I agree with, but odds and probability are not the same thing. See Jacobian's post #5.

Odds is a gambling term and are calculated by the number of people who think "A", compared with the number of people who think, "NOT A"; this is why odds change in a horse race.

In a horses race, there is no way to calculate the probability of a particular horse winning, other than, perhaps to say, there are 6 horses in the race, only one can be a winner, therefore any horse has a 1:6 probability of winning.

Probability refers to mechanistic objects and concepts - those that are susceptible to mathematics. A roulette wheel is entirely random and we can speak of the probabilities of red or black, odd-even, or a number, etc. arising.

To see how the odds differ mathematically from probability, see #5

#### coolieinblue

##### Banned
I think all of you are addressing a very difficult subject on empircal probability and mathmatical probability.

My random guess :
odds : empirical turnouts
probability : theoretical possibility

#### morzh

##### Banned
In colloquial speech I see them used in the same situation, with the difference of:

- The odds are good/bad
- The probability is great/small

Still, many folks will use them interchangeably.

- What do you think the odds of that happening are? - Not too good. / 1 to 10 / 10 to 1 against me.
- The probability of that happening is extremely small.

PS. There is also "chance".
- The chance of this happening is very low.

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#### coolieinblue

##### Banned
morzh, much to the point again.

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