Thanks to all who post here. I have learned a lot by reading topics in the think tank. I finally decided to join and post a question...
Of particular interest to me is the idea of a statistically significant sample size. I read through the idea of z-scores etc.... looked at the binomial calculator as well.
I bet NBA sides and MLB totals - that's it; I don't really bet other sports, I am disciplined, I don't have cable, I don't watch the games I bet on.
I flat bet, no stars or multi-unit games. I simply bet 1 unit per game.
I keep records in an excel file every year for each sport.
I am trying to determine whether or not I believe that I am good enough to increase my bet size next season in NBA sides - whether I believe my winning percentage is a result of handicapping ability or that luck created (some or all of) the results.
For 2007-2008 NBA season I was 234-161 ATS (I only bet sides). I immediately thought this result had to be helped out by some lucky breaks because of how high the winning percentage was at around 59%.
As I suspected, the next year it came down to earth a little bit; but there was a slight change in approach.
In 2008-2009 I began using matchbook and selling half points on nearly every game I bet. I used the half point calculator to find +EV spots, and I also did it in break even spots because I hate laying -juice. So, when you start selling half points your raw percentage is going to drop but your units should increase or stay the same, which is all that matters.
In 2008-2009 my raw record with selling points was 220-197 = 52.76% but my average vig was probably about -101 or -102 instead of the previous season laying -110 and getting better lines. I ended up +19.7 units that season, flat betting 1 unit per game. Had I not sold points my record would have been about 54.6% which would give the same amount of units at -110 over the same number of games-- a record of about 228-189 over the same number of games at -110 ~+20 units.
So over the course of two seasons I am either a raw 454-358, or probably a more accurate 462-350.
So the bottom line is, do you think this is a large enough sample size of games?
Using the binomial calculator I get
0.0004 if I use n=812, x=454, p=0.5 (at least 454)
0.00005 with n=812, x=462, p=0.5 (at least 462)
I am tempted to believe that the results are not solely that of luck, but I was curious to see what others use to quantify their results.
Am I missing anything? I am either 55.91% with the raw numbers or 56.9% with the adjust numbers from 2008-2009. This seems to be a real result with a realistic winning percentage over a large number of games.
I am starting to believe in my ability but is there anything I am missing? I just don't want to fool myself into drinking my own kool-aid too soon. I thought 2 full seasons would be enough but ....
Should I be looking at the numbers differently? Should I be using a different tool than a binomial calculator?
Thanks to all who read and/or respond