Originally Posted by
lauraa:
“i know this is gonna sound stupid, but how do you know whos favourite? i dont get what the figures mean 
”
You can think of odds as an indication of probability (of winning Strictly in this case).
To simplify, let's pretend for a moment that the bookmaker doesn't make any profit. A charity bookmaker (as if).
Matt is 4:1 which as a ratio is the same as 80:20.
In other words, Matt has a 80% chance of losing and a 20% chance of winning (according to the betting market).
Willie is 9:1 which as a ratio is the same as 90:10.
In other words, Willie has a 90% chance of losing and a 10% chance of winning.
If Richard Hammond, say, was taking part he would perhaps have odds of around 1:3 (described as 3:1 on) which as a ratio is the same as 25:75.
In other words, Richard would have a 25% chance of losing and a 75% chance of winning.
Now of course the bookies have to make a profit so the actual probabilities of winning are lower than this....but can be calculated fairly easily.