Hi!
Question belongs to the same topic so I hijack your thread, hope thats ok.
I have analysed over 3000 picks, which I get from the Odds Archive. They show good profit but in reality I get a much smaller ROI. Not bad but I looked for the problem.
One thing came to my mind during entering the results. There I found out that the pick has changed from Hometeam in Reality to the Awayteam (according to OW odds < Bookie odds).
some Example.
The updated results for Scottish third League shows me in OW software
Albion - Elgin 1.89 3.94 4.58
in your archive file:
Albion Rovers FC- Elgin City FC 2.15 3.75 3.72
Elgin won by 3-0.
No other games where played on this gameday before.
So In assume that you sometimes take the new odds AFTER the result was priced in, what makes backtesting senseless obviously, or are there other reasons why the pices could change without league games beeing played?
Other leagues (e.g. France Ligue 1, Dutch Eredivisie) are spot on.