Stabilize all-in-one metrics

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ransourui
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Joined: Sun Feb 25, 2024 8:18 am

Stabilize all-in-one metrics

Post by ransourui »

I want to predict not-started season contribution of player by completed season data.
Predicted ratings are good or bad extremely when players who play few minutes record good or bad stats extremely.

So, I make a method that stats are regressed to mean, then calculate all-in-one metrics. I called this methods 'linear padding'.

Linear padding is realized using linear regression models. For example, let's consider prediction 2022-23 season EFF (efficiency), the simplest all-in-one metric , by older data. In this example, stats are per 36 minutes adjusted then EFF is calculated.

To calculate linear padded pts, pts each player in 2021-22 season are regressed by pts each player in 2020-21. Regressions are performed each stats that using to calculate EFF. These regression models are used to predict each stats in 2022-23 season by 2021-22 season stats. Predicted 2022-23 season stats are used to calculate EFF.

Using data in Japanese professional basketball league (B-League) 2021-22 season, I compared correlation coeficient between linear padded EFF or raw EFF and 2022-23 season EFF. I also calculate RMSE. In results, using linear padding makes correlation higher(0.869 vs. 0.854, p<0.01) and RMSE smaller(2.41 vs. 2.53).

Using linear padding, between season correlation of EFF is higher and predictive error is smaller than using raw stats. So, I guess not only EFF but also more sophisticated metrics improve stability using linear padding.

Please tell me other methods that improve all-in-one metrics' stability. Thanks.
DSMok1
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Joined: Thu Apr 14, 2011 11:18 pm
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Re: Stabilize all-in-one metrics

Post by DSMok1 »

Nice work!

Padding statistics to achieve stabilization is an informal form of using a Bayesian prior, i e information about the overall talent pool distribution, to regress the data toward a reasonable prior. There are a number of articles on the topic.

Kostya Medvedovsky wrote one of the best summary articles on the topic here: https://kmedved.com/2020/08/06/nba-stab ... -approach/

In essence the whole DARKO projection system is using an advanced form of this approach to achieve Bayesian projections for each statistic.
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