[npc]

I'm not knocking the OP, but I REALLY HATE this forum's software. One misstep and a lot of writing is lost. This will probably be the last long post I'll reply to with proper context.

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I'm working with an NHL database to come up with some over/under percentages for various periods. I have all of the games from this current season for every time broken down by period.

...

Example: Detroit goes under 54.55% of the time and PHI goes under 43.64% of the time.
If they are playing each other, that becomes an average of 49.09% on the under.

I hope everyone can follow me so far. Everything seem logical up to this point?

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As long as one opponent is above average and one is below average, this is fine. If both are above or below average this method is badly flawed. I hope you can see why.

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My problem: How do I incorporate this goalie number into the averages I have for the OVER/Under?

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Here's how I'd do it (and how I've done it for baseball totals). I'd record who the goalie is for each game and treat each "team:goalie" combination individually. This eliminates your problem.

I haven't carefully analyzed your results, but I'm guessing that your math problem is due to the fact that each goalie hasn't played half of all games. So, no matter what, you have to track how many games are played by each goalie so you know how to weight your percentages, so you may as well break their stats out separately.

Make sense?