[dsteff]

You're making a couple of important math mistakes throughout.

The first is that you're not recognizing the difference between median and mean. When working with small numbers (such as goals in a period) this can be a significant mistake. For example, a team that scores an average of 4 goals a game may seem like a good bet to score more than 2.5 goals in their next game. However if that team has scored 2, 2, 2, 2, and 12 goals in the five games they've played they have been under the 2.5 line four out of the five times.


This is a median based calculation:
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Detroit goes under 54.55% of the time and PHI goes under 43.64% of the time.

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This is a mean based calculation:
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If Goalie #1 gives up 3.09 goals per game, he would be 118.39% ABOVE the average for the team.

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You cannot calculate a weighted O/U % from these two statistics alone.


The second math mistake is related. In your final calculation you attempt to multiply % O/U and % goals. These two units don't match. You're attempting to factor in the goalkeeper way to late in your calculation. As npc suggested a good solution would be too keep your data separated by team:goalie then do the calculations from there.