Query re Betfair Order of Runners

[johnboy]

Hi
Can anyone please give me an idea as to why some runners will change order on Betfair's list as their price changes but others can say become favourite and still be placed at say second, third or fourth in their order of runners.
Thanks

Johnboy

[spreadbetting]

I think Betfair usually do the order by reduction factor so sometimes the order will change depending on when you entered the market if Betfair have done a change to the RF. Once you've entered a market the order should be fixed though not jumping around.