Make Your Own Rating
So, you want to make your own computer ratings. Welcome, friend!
Step 1: What is your goal?
Do you want to predict winners, i.e., margins of victory and/or totals?
Or, do you "only" want to rank teams based on their accomplishments to date?
These two goals are not always the same. Side note: in the old days, you might have heard these referred to as "predictive" systems vs. "retrodictive" systems. I don't like that word, but that's what we had and what some of us still use.
Your choice of goal -- either of those, or both simultaneously -- is a key question you must answer first.
Step 2: What are your values?
There are lots of aspects of a season of games that you may, or may not, want to weigh. Each question below links to some brief thoughts of my own, plus other ideas that I've culled from around the web. (All are works in progress!)
- Should more recent games be weighed more heavily, or is every game in a season of equal importance?
- Should the location of the game matter?
- Should scores and margin of victory matter? Or do you believe that "a win is a win?"
- Should "running up the score" be rewarded? Or does the principle of diminishing returns apply after a certain margin of victory?
- Do you want to include other aspects of a team's performance beyond the scoreboard? (Yards gained, shots blocked, corner kicks taken, whatever...)
- For big sports, do you want to rate everyone, or are you only interested in a subset of teams? (For example, there are over 1000 NCAA men's basketball teams, from Division I to II to III...)
Again, these are all questions that you probably need answers to before you begin.
Step 3: Can you write code?
[to be written]
Step 4: What kind of mathematical method should you use?
[to be written]
Step 5: Collect your data
[to be written]
Step 6: Now, let's do it.
[to be written]
Quick Links
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