Thread: Theorycrafting: The likelihood of drawing SR and SSR kamihime in Gatcha

Originally Posted by Unregistered

By the way, with my results, I'm getting nowhere near 50% chance of SSR Kamihime for $98 (3.3 rolls).
My calculations show it to be 50.184% chance at 6.3 rolls.

You're misreading the table. The category rates are the rate of pulling a given type (kamihime, eidolon, weapon) within a given rarity tier. They're estimated from empirical data and used to generate the subsequent tables. This method is less subject to random biases because the category rates are much higher than the rate of obtaining a SSR, dampening the impact of variance. Also, we know the rarity rates exactly; they don't need to be estimated.

This misunderstanding happens frequently so I've revised the table to try and be clearer.

Also, I have no idea where you're getting the 50% chance of SSR kamihime from 3.3 rolls. My spreadsheet currently shows that a 50% rate is achieved at 4.8 10-rolls.

Originally Posted by sanahtlig

Also, we know the rarity rates exactly; they don't need to be estimated.

This misunderstanding happens frequently so I've revised the table to try and be clearer.

Also, I have no idea where you're getting the 50% chance of SSR kamihime from 3.3 rolls. My spreadsheet currently shows that a 50% rate is achieved at 4.8 10-rolls.

1. Where are the exact rates?
2. The 50% from 3.3 rolls is from your 4th/5th tables in your OP, where it states 3.3 rolls $98 for 50% chance of SSR Kamihime. Using 1.1% SSR Kamihime probability, 50% occurs at the 63rd roll, not 48th roll.
Formula is 1 - (1 - r)^n = p
where:
r = rate per pull
n = number of pulls
p = probability of at-least 1 pull of r rate

- - - Updated - - -

Formula is 1 - (1 - r)^n = p

So if we want to isolate n...
(1 - r)^n = (1 - p)
n * log(1 - r) = log(1 - p)
n = log(1 - p) / log(1 - r)
n = log(50%) / log(98.9%) = -0.30102999566398119521373889472449/-0.00480370840282059472713473451959
n = 62.666167556553876882697804745512

Originally Posted by Unregistered

1. Where are the exact rates?
2. The 50% from 3.3 rolls is from your 4th/5th tables in your OP, where it states 3.3 rolls $98 for 50% chance of SSR Kamihime. Using 1.1% SSR Kamihime probability, 50% occurs at the 63rd roll, not 48th roll.
Formula is 1 - (1 - r)^n = p

1. The game states that the SSR rate is 3%.
2. I multiply that 3% by the category rate for kamihime in the SSR tier (47.83%). That equals a SSR kamihime rate of 1.43%, not 1.1%. That's likely why our end results are different.

Originally Posted by sanahtlig

I've updated the OP with the results of my analysis. Updates include:

1. Incorporation of data from 1000 rolls to empirically determine category rates (kamihime vs. non-kamihime weapon vs. eidolon).
2. Factoring in the guaranteed SR+ in 10-rolls.
3. Added an estimate of the total # of kamihime of a given rarity one could expect from N 10-rolls.

The results should now be robust for R and SR, and approximate for SSR.

Sanahtlig's Kamihime Project R Theorycrafting

Sorry to necropost but I'm curious if this data changed at all with the gacha removing non-hime SSR weapons from the mix? Is it safe to say it's still approximately $200 USD for a SSR kamihime?

Originally Posted by Saberborn

Sorry to necropost but I'm curious if this data changed at all with the gacha removing non-hime SSR weapons from the mix? Is it safe to say it's still approximately $200 USD for a SSR kamihime?

Is it confirmed that non-kamihime SSR weapons have been removed from Premium and Jewel Gatcha?

Originally Posted by sanahtlig

Is it confirmed that non-kamihime SSR weapons have been removed from Premium and Jewel Gatcha?

See 12/10/17 news post. I can't verify its validity beyond that.

Originally Posted by Saberborn

See 12/10/17 news post. I can't verify its validity beyond that.

Sadly, I don't consider official news bulletins on Nutaku to be a reliable info source (not with all the misinformation they put out). I need confirmation that people who've done hundreds of 10-rolls of Jewel Gatcha haven't gotten any SSR weapons without kamihime.

Originally Posted by sanahtlig

Sadly, I don't consider official news bulletins on Nutaku to be a reliable info source (not with all the misinformation they put out). I need confirmation that people who've done hundreds of 10-rolls of Jewel Gatcha haven't gotten any SSR weapons without kamihime.

I've been re-rolling for weeks (almost 6 weeks) and I can confirm that I haven't get a single kamiless weapon from the Jewel Gacha for a while now. Only Kamis and Eidos.

Originally Posted by Laventale

I've been re-rolling for weeks (almost 6 weeks) and I can confirm that I haven't get a single kamiless weapon from the Jewel Gacha for a while now. Only Kamis and Eidos.

Alright, I adjusted the category rates to remove kami-less weapons from the SSR rarity tier. It actually doesn't change the rates much since the kami-less rate was already low.