Scores and Sigma Explained
Scores and Sigma Explained
How a rare item's score and sigma are calculated, and what they mean.
Dec 18, 2021
Categories
General
Date
Dec 18, 2021
Post by
ozzy
Score
A rare item's score is calculated by multiplying each roll by the weight for that mod. The intention is for a "perfect" ring to have a score of 100.
This value is static. It is calculated purely off of the ring itself, and does not take in to account the rest of the rings in the database. It will not change, unless the weights change.
The math is straight forward:
Ideal score = sum of top 6 weights for the specific useCase
Weight for each mod = (roll / max roll) * ModWeight
Total weight for each rare item = sum of weights for each mod
Score = Total weight / ideal score * 100
Sigma
The sigma value represents how many standard deviations above or below the average the score is.
Because this value depends on the average and standard deviation of the total population then it will change as more items are added to the database. If you notice the sigma score changing over time just be patient. As the database grows larger these fluctuations should get smaller and smaller.
For example, if the average score for all rings is 40, and the standard deviation is 10:
| Score | Sigma |
|---|---|
| 20 | -2 |
| 30 | -1 |
| 40 | 0 |
| 50 | 1 |
| 60 | 2 |
To calculate the standard deviation we assume a normal distribution.
By M. W. Toews - Own work, based (in concept) on figure by Jeremy Kemp, on 2005-02-09, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=1903871
You can use the sigma value to assess how this ring stacks up vs the other rings in the database.
| Sigma | Better than % of all other items |
|---|---|
| -2 | 2.3% |
| -1 | 15.9% |
| 0 | 50% |
| 0.5 | 69.1% |
| 1 | 84.1% |
| 1.63 | 90.3% |
| 2 | 97.7% |
Is this Charsi food?
The color coding on this site is based off of the maximum sigma value from all possible use cases.
| Color | Charsi message | Minimum sigma | Better than % of all other items |
|---|---|---|---|
| green | Definitely Keep | 1.0 | 84.1% |
| yellow | decent | 0.0 | 50.0% |
| red | Charsi Food! | N/A | N/A |
If the sigma value is near the threshold between two of these states, then you may observe it switch back and forth as more items are added to the database.
When in doubt, use your own discretion and judge the ring based off of the score, which will remain static regardless of how many items are in the database.
Contact
Official d2CharsiFood.com discussion thread on FragmentShader.com
I am very interested in your feedback!
contact me.
Join the Discord
Email: ozzy@d2charsifood.com
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Comments :
Efolker23 Nov 23, 2022
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Contact
Official d2CharsiFood.com discussion thread on FragmentShader.com
I am very interested in your feedback!
contact me.
Join the Discord
Email: ozzy@d2charsifood.com
Battlenet: streetlights#1689
Discord: coolshoeshine#4818
Social media:
Donate
- Bitcoin: 1P4kBPyFoR6xa4sy2hnHL3oY6sg4PrXn6M qr code
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