btcl....what am i missing?

[slapshot]

been reading threads on beating the closing line here.

the idea outlined behind btcl is that if you constantly bet at a better odds than the line is closing at, you will be profitable.

my question is, how is that possible if your winning percentage isn't high enough?

i could be beating the closing line constantly, for example betting 100 teams at -110 when they closed at -130....but my teams only came through 45 times.....certainly no profit there.

if you take for granted that winning percentage is high enough to generate profit.....why would beating the closing line matter?

obviously you'd be more profitable beating the closing line rather than losing to it.......but value and winning percentage comes before btcl or what am i missing?

[HeeeHAWWWW]

On the first point: you're right, you need to do more than btcl by a little, but enough to cover the juice too.


As to why it matters: it's an indicator of future profitability. Why? Because, on average, the closing line is generally pretty accurate. If you're repeatedly beating that by a solid margin (as above, enough to make profit), it's a strong sign you've been betting value. By contrast, you can "make money" for a lengthy period solely based on luck - something most gamblers never realise.

Btcl is most useful in gambling because statistical methods of measuring your results against chance (for example z-score) require fairly gigantic numbers of bets.

[u21c3f6]

What you are missing is the theoretical value.

Let's assume that the actual value for the 100 teams you bet at -110 and closed at -130 is actually -120. That means that theoretically you should win 6 out of 11 wagers or 54 or 55 of your 100 wagers which would then show a profit.

Joe.

[gamblingisfun]

What if a person beat the closer at say 60% by 20 cents every time they beat it, but the other 40% got killed by it and lost by like 30 cents? Would that person say they beat the closer by 20 cents and only count the times they beat it? Or average in the times and the amount they lost to it to come up with what they could say they consistently beat the closer by for their bets?

[HeeeHAWWWW]

What if a person beat the closer at say 60% by 20 cents every time they beat it, but the other 40% got killed by it and lost by like 30 cents? Would that person say they beat the closer by 20 cents and only count the times they beat it? Or average in the times and the amount they lost to it to come up with what they could say they consistently beat the closer by for their bets?

It's certainly important how much you beat/lost to the line by, because that's directly related to how much value you're getting (or not getting).

A lot of people just use a flat % approach - ie they beat the closer 53% of the time, or whatever. This is fairly useless, because it ignores the overall level of juice, and the degree to which the player beat the line.

Once you get sufficient sample size of your bets with the closers recorded, a more advanced test is to split your bets into bands relative to the closer, say into quintiles. So the bottom quintile, you sucked ass relative to the closer, perhaps it went 15% the wrong way. The 2nd quintile you did a bit better, hopefully nearer zero, etc etc, and by the top (5th) quintile you absolutely destroyed it. Calculate the RoI for each band, then correlate those RoIs against the medians of the bands. With a large enough number of bets, you can thus prove RoI correlates very precisely with how the line moved.

[lamichaeljames]

It's certainly important how much you beat/lost to the line by, because that's directly related to how much value you're getting (or not getting).

A lot of people just use a flat % approach - ie they beat the closer 53% of the time, or whatever. This is fairly useless, because it ignores the overall level of juice, and the degree to which the player beat the line.

Once you get sufficient sample size of your bets with the closers recorded, a more advanced test is to split your bets into bands relative to the closer, say into quintiles. So the bottom quintile, you sucked ass relative to the closer, perhaps it went 15% the wrong way. The 2nd quintile you did a bit better, hopefully nearer zero, etc etc, and by the top (5th) quintile you absolutely destroyed it. Calculate the RoI for each band, then correlate those RoIs against the medians of the bands. With a large enough number of bets, you can thus prove RoI correlates very precisely with how the line moved.

I will try this tonight.