I will use hockey stats as an example for what I want to do. I basically want to combine various statistics of a given "hockey player" to get an overall point total that represents him.

For example, a player who has 20 goals, and 30 assists. What I already know how to do is, I would add up all the goals scored in the entire league, and all the assists, and see how many assists there are for every goal, find the ratio between the two stats. Let's say I found out there were two assists for every one goal.

At this point it's easy. I choose a value to give to an assist, say 5 "points," and then because goals are twice as rare as assists, a goal would be 5 points times 2 equals 10 "points." So if assists are worth 5 points, and goals 10, and he has 20 goals and 30 assists, then it's just 20 goals multiplied by 10 points = 200, plus 30 assists multiplied by 5 points equals 150, 200 + 150 = 350. So this example hockey player, between those statistics, has the value of 350 points.

That part is easy. Here is what I don't know how to do. In hockey, and also with the statistics Im dealing with for my project, there are stats that range into the negatives. In hockey, there is a stat called plus-minus. For every goal your team scores while you are on the ice, you get a plus one. For every goal that is scored against you while you are on the ice, you get a negative one, and these compile over the season. Some players get as high as plus 40, some as low as minus 40, but every year it is different. And because approximately half the players end the season with negative plus-minuses, and half end with positives, you can't just add them up like you do with assists. Adding all the negative plus-minuses with the positive plus minuses is just going to land you smack in the middle, somewhere around zero. Say you even ended with 10. If I add up all the goals scored, and it's 3000, for example, and I end up with 10 plus minus... 1 plus-minus point is worth 300 goals? No. Goals are more rare than a plus-minus point, not less rare.

So how do I equate for this? For assists and goals, both strictly positive statistics, I could just add them up to find the ratio. 3000 goals scored this year, 6000 assists? That means 2 assists for every goal, 2:1 ratio. But because half the plus-minuses approximately are negative, I cant add them. So how do I find the ratio? How do I figure out what value to give a plus-minus point in relation to goals?

Thank you for your help!