I created an NFL betting system in excel using the following inputs team home win% away win% weather venue final score no of try's conversions ********s tackles.

How do use that information to predict the outcome of the game as a probability is there a excel formula I can use.

All this information is from the last 2 years of the nrl

If your system is producing a score for each of the sides, you can produce a graph mapping how often teams win given your predicted margin between the two. Then use Excel's Solver function to discover the curve that best describes the relationship. Now, for future games, when you determine the margin is 10 points, you can use the formula of the curve to say that your predicted winning team has a 60% chance of actually winning.

I go into a tiny bit more detail and show a graph in this post: http://www.ozmium.com.au/forums/sho...959&postcount=2