I noticed that the bookmaker's edge is much smaller when there is a big favourite involved.
For example, when the odds are 1.001 for the fav and 63 for the dog the edge is 1.49%. On the other hand, if you have odds of 1.96 and 1.96 (which to me seems much more fair) the edge is 2.04%.
Is there any explanation for that or am I confused? Thank you.
I think your question needs clarification. Where did you come up with those numbers? What do they represent? I am having problems determining what you want answered.
If you have odds of 1.85 and 1.85 the overround (house edge) will be 1/1.85 + 1/1.85 = 8.1%. But as the spread between the favourite's line and the dog's line increase the overround will decrease as well. For odds of 1.1 and 7 the overround is 1/1.1+1/7 = 5.2%. For odds of 1.001 and 100 you have overround of only 0.89%. This makes me wonder if you are better off betting on lines with big spread.
So for the odds I mentioned, the theoretical hold will be:
For 1.85 and 1.85: 7.5%
For 1.1 and 7: 4.9%
For 1.001 and 100: .88%
Similarly, the theoretical hold decreases as the spread of the line increases and I have no explanation why that happens. Hopefully my question is clear now.
Unsophisticated bettors are generally put off by seemingly large absolute differences between back and lay prices. The bookmaker must balance this perception with maintaining her hold. A surprising number of bookmakers probably fail to completely grasp the concept of theoretical hold themselves.
So do you think a bettor is better off developing strategies for bets with large absolute differences between back and lay prices? In this case, the expected value is approximately -1% compared to approximately -5% when the lay and back odds are very close. It seems easier to beat 1% than 5% but I haven't noticed a tendency of pro bettors focusing on bets with large absolute differences between back and lay prices.