Quote:
Originally Posted by tyler522
Ray, been using Betmix , what win% , ROI & results size do u feel is acceptable when running data? I use 5 years, however at time results yields 15 horses 6 wins win% 40% return $47 ROI % 256. From ur experience what is the sweet spot for # results # wins win%? ROI% ? Thanks in advance
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When it comes to Win% the short answer is 500 races.
The long answer is you have to ask the question this way . .
How many races do I need to be 95% sure that my Win percentage is real, plus or minus 4 percentage points.?
Formula N = (SQRT(p*q)^2*Z^2)/(E^2)
p = estimate Win % (Example 40%)
q = 1 - p
Z = 2 for 95% sure
E = acceptable margin of error (Example .04)
N calculates to 576
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When it comes to ROI, it's much more complicated and I've never found a good layman's discussion. There might be one in the T-Bred Forum but it's a tough search.