Bookies

[PeterR]

I am looking into the usability of betting odds for events like BREXIT.

But I don't know anything about betting. (I never gambled in my life.)

For Brexit the odds showed the "Remain camp" as leading till midnight Thursday-Friday.
Only then the spread closed and finally flipped.



My question is how do Bookies calculate the odds they offer ?

Is it

• A) A function of X amount of people betting on "Camp Remain" vs X amount of people betting on "Camp Leave". The Bookie knows these numbers and offers the ratio as odds plus a spread. The Bookie does not need to have an opinion about the topic.
  
• B) The Bookie actually formulates an opinion and bases the odds offered on that opinion.
  
• C) a mix of A & B

Does anyone know ?

I suspect it is A) and we get the cumulative knowledge of all people that bet.

Yet I wonder what influence the bookie has over the odds.