Thanks MarkV. I see what you mean. I didn´t realized that that function was based in all volume since the market opened in the Betfair. Now I see why it doesn´t move much.
So for example, an horse have @10.55 SP and during the race the odd moves up an down, like every horse. If the the odds (back and lay) down to @7.5 to back and @8.0 to lay, how can I calculate this down size compared to SP? Because, by my understanding, the odds can move without being matching money.
Example: SP @10.55
Lay / Back
@10.00 / @11.00
@10.50 / @12.00
@9.80 / @10.50
@9.60 / @10.00
@9.00 / @9.60
etc.
Is it possible to calculate these average prices offered in live and for a certain time?
Thanks for your attention.