Mystery Island RNG Pattern - solved with data and stats tests

ctar17

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Hello all,

There is lots of talk about the specific pattern that is used for villagers on mystery islands. I would like to present my findings in this thread and open it up for possible statistics discussions to confirm this theory even more.

First, I'd like to thank Selkie for sending me their data to perform statistical tests on and Sheba and ForbiddenSecrets for bringing up the theory in the first place. The theory is that the game first rolls for a species. Once the species is chosen, it then rolls for a specific villager in that chosen species. The game does NOT roll for a specific villager right off the bat.

Here is the thread where this theory was initially proposed:

The way the tests were done are pretty straightforward. People have been noticing the octopuses appearing a lot more than they should as there's only 3 of them. Therefore, I tested to see if the number of octopuses that actually appeared in the sample was statistically significant than the number of octopuses that we would expect to appear in the sample.

Earlier today, before this theory was brought up, I performed a Chi Square test on Selkie's data to check if it was completely random or pseudo-random or if there was a pattern. Selkie's data has a sample size of 344. The expected chance of an octopus appearing using the old theory of the game randomly rolls a villager from the pool of 391 is 3/391. In the data we would expect one to have about 2.56 appearances in the 344. The data contained 12. Here is the Chi Square test for this model:
chi square complete.JPG

As you can see, the Chi Square value is larger (much larger) than the value that produces a p-value of 0.05 for a Chi Square test with 1 degree of freedom (the p-value that is produced with 35.01 is less than 0.00001). This concludes that the observed and expected are indeed statistically different. Therefore, the game does NOT just choose a villager at random out of the 391.

After seeing Sheba's thread and ForbiddenSecret's reply with the species first theory, I decided to go back to Selkie's data and perform another Chi Square test using the parameters that the game chooses a species first at random then a villager in that species. Using this, the expected chance of an octopus is 1/35 not 3/391. In the sample of 344, we would expect the octopuses to have 9.54 appearances. Here is the new Chi Square test:
chi square species.JPG

As you can see, the Chi Square value is less than the value that produces a p-value of 0.05 for a 1 degree of freedom test (the p-value that 0.65 produces is 0.42). This means that we cannot reject the null hypothesis of "The game randomly rolls a species of villager first" I conclude that the theory that the species is rolled first then one is selected in that chosen species is basically correct.

What is a Chi Square test?
Basically it tests whether 2 groups of data are statistically different. A common use of it is to test whether your observed set of data is statistically different (not due to random chance) from the expected data.

UPDATE: I have now tested (with the help of more data from TBT users) to see if this theory applies evenly across the board, only 2/35 species didn't uphold the theory, but that is not enough to disprove it all together, and I can attribute it to the nature of RNG. I conclude that it does! The chance for a specific species to be rolled is the same for every species.

UPDATE 2: While I have not formally conducted tests on if the game rolls for personality after species or just rolls straight for a villager yet (still working on this), my initial analysis of the new data provided suggest that this is NOT the case. The game does NOT roll for personality at all (villager 1-5 are locked personalities). I'm 95%+ sure this is the case, but can't outright solidly confirm that there is no personality roll. Nor does lacking a personality on your island increase or decrease the chances for that personality to appear on mystery islands. This also applies to what species you have as well, it won't increase or decrease the chances for a species to appear if you already have 1 or more on your island.

Thanks again to Selkie, Sheba, and ForbiddenSecrets for providing data and/or the theory!

Happy hunting!

Now the big question that a lot of you are wondering...
What does this mean for Raymond hunting?
Well, I'll tell you. The cat is even more elusive than we originally thought! It means that the chance to find Raymond on mystery islands is very low. It's lower than 1/391 because there are 20+ cats in this game. In fact, I have calculated the chance to find Raymond on a mystery island to be about 0.12% Basically 1 in a 1000. Good luck!
Other has pointed out a theory that lacking a smug will cause random move ins, i.e. letting the plot fill up, to be smug. Sounds like this is a much better bet, especially if you're willing to TT to force out the smug to try again!
 
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Does that mean that getting a villager of any given species is uniform? (i.e. two different species are equally likely to be drawn)
 
That is a lot of work! Thank you for your contributions to the community! :D I was able to find Reneigh today on a mystery island and now I realize how lucky I was! Hopefully, we will be able to figure everything out soon! I'll use this information when hunting for a villager for my next plot!
 
Does that mean that getting a villager of any given species is uniform? (i.e. two different species are equally likely to be drawn)

I think this is correct. If the game rolls species first, then I would assume each species has an equal shot of appearing (1/35) While I only did this test with the octopuses and found the theory to hold, I would make the assumption that this applies to the others as well.

1/35 is a little less than 3%, so if you're going for a specific species, it could take a while!
 
Hi, I forgot to ask over the other thread. Will your chances increase when you have one of the species in your island. Like you mentioned previously, I have 0.24% chance to get Kid Cat or Raymond. I have Felicity on my island. Does this mean my chances will increase?
 
Hi, I forgot to ask over the other thread. Will your chances increase when you have one of the species in your island. Like you mentioned previously, I have 0.24% chance to get Kid Cat or Raymond. I have Felicity on my island. Does this mean my chances will increase?

Hi, I do not have the data to test this at this moment, but I would suspect that it doesn't in the way you're talking about...
I could test this out with more data eventually to find out though, my next plan is to test whether there's a different roll for personality after the species one

it will provide a slight increase as Felicity is removed from the cat pool. Your new chances are 0.260% A VERY slight increase
 
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Hi, I forgot to ask over the other thread. Will your chances increase when you have one of the species in your island. Like you mentioned previously, I have 0.24% chance to get Kid Cat or Raymond. I have Felicity on my island. Does this mean my chances will increase?
Theoretically, yes, but not in the way you're asking. After analyzing the data and comparing it with my own experience (I'm about 500-600 tickets deep getting my villagers) I can probably attest that the game rolls on species first then decides on a random villager of that species. With that in mind, it makes targeting the more common species (i.e cats and dogs) harder. If the odds are the same across all species but the pool of available villagers differs largely you suddenly have villagers that will be more common than others. You're more likely to encounter Marina WAY more often compared to any cat villager, for example.

This is really disappointing, honestly. Considering dogs, rabbits and cats have the most villagers per species it just makes targeting a specific villager within that pool much harder (ie. Raymond or whoever).
 
I think this is correct. If the game rolls species first, then I would assume each species has an equal shot of appearing (1/35) While I only did this test with the octopuses and found the theory to hold, I would make the assumption that this applies to the others as well.

1/35 is a little less than 3%, so if you're going for a specific species, it could take a while!
Would you be willing to publish all of the data?
 
Theoretically, yes, but not in the way you're asking. After analyzing the data and comparing it with my own experience (I'm about 500-600 tickets deep getting my villagers) I can probably attest that the game rolls on species first then decides on a random villager of that species. With that in mind, it makes targeting the more common species (i.e cats and dogs) harder. If the odds are the same across all species but the pool of available villagers differs largely you suddenly have villagers that will be more common than others. You're more likely to encounter Marina WAY more often compared to any cat villager, for example.

This is really disappointing, honestly. Considering dogs, rabbits and cats have the most villagers per species it just makes targeting a specific villager within that pool much harder (ie. Raymond or whoever).

Yup this exactly! If a species has more than the average number of villagers/species, all villagers in that species will be statistically harder to find than 1/391
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Would you be willing to publish all of the data?

For all of the data, I do not have the specific names as I just asked for how many octopuses you got in a specific number of islands as the specific names were not needed for the test, only the species. I have requested the full data, and am open to DMs of more data to perform additional tests! I was just given "I got 12 Octopuses in 344 islands" which was enough to perform the test to confirm this theory. I'll go back to retest the theory if it still holds when I get more specific data
 
Yup this exactly! If a species has more than the average number of villagers/species, all villagers in that species will be statistically harder to find than 1/391
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For all of the data, I do not have the specific names as I just asked for how many octopuses you got in a specific number of islands as the specific names were not needed for the test, only the species. I have requested the full data, and am open to DMs of more data to perform additional tests!
I'm interested in species count, so what you have is good enough for me.

EDIT: Wait, was the dataset just octopus/not octopus?
 
I'm interested in species count, so what you have is good enough for me.

All I have for now is what's posted as I specifically used Chi Square because it doesn't require too much and it's easy to use to test out the RNG theory, just how many you got out of the total number really. I specifically asked for the report on octopuses as there's not many of them and they are memorable so I figured it would be more accessible for people to collect data.

Others have reached out offering me more data to analyze if this holds for all species (which I would assume it does, and the original conjurers of the theory assumed so as well) The thread posted in my original post is a good resource of data as well.

And yes, it was just octopus/not octopus. I originally did it to test if it was pulling a villager straight out of the total 391 pool or not. It's enough to look at and support the species first theory as well, and combined with others noticing this trend, I would say this theory is currently the best we've got
 
Ohhh now I see why octopi are more common now, I was questioning before why I see a lot of octopi in island tours, then with that data species with more villagers would be rarer now (especially if you're looking for one specific villager of that species) in comparison with species with less, that's very interesting to know, thanks for conducting this test :D
 
Ohhh now I see why octopi are more common now, I was questioning before why I see a lot of octopi in island tours, then with that data species with more villagers would be rarer now (especially if you're looking for one specific villager of that species) in comparison with species with less, that's very interesting to know, thanks for conducting this test :D

Yup and combine that with the Octopuses unique look and there was definitely a trend of "heyyyy I'm seeing a lot of Octopuses!" Techinically they have the same 1/35 chance as any other species, but since there's only 3 of them, these 3 specific villagers will appear a lot more than villagers in species with 20+ like cats (sucks if you're hunting for He Who Shall Not Be Named), and this will cause your brain to pick up on seeing more octopuses as well
 
Yup and combine that with the Octopuses unique look and there was definitely a trend of "heyyyy I'm seeing a lot of Octopuses!" Techinically they have the same 1/35 chance as any other species, but since there's only 3 of them, these 3 specific villagers will appear a lot more than villagers in species with 20+ like cats (sucks if you're hunting for He Who Shall Not Be Named), and this will cause your brain to pick up on seeing more octopuses as well
The hunt for He Who Must Not Be Named would be tough indeed AHAHAHAHA
 
Yup and combine that with the Octopuses unique look and there was definitely a trend of "heyyyy I'm seeing a lot of Octopuses!" Techinically they have the same 1/35 chance as any other species, but since there's only 3 of them, these 3 specific villagers will appear a lot more than villagers in species with 20+ like cats (sucks if you're hunting for He Who Shall Not Be Named), and this will cause your brain to pick up on seeing more octopuses as well

LOL @ bolded part... yes
and this makes a lot of sense! i know this took time thanks because plenty of us have been wondering. makes sense why i keep seeing repeat villagers too, it has to be rolling species first.
 
The hunt for He Who Must Not Be Named would be tough indeed AHAHAHAHA

LOL @ bolded part... yes
and this makes a lot of sense! i know this took time thanks because plenty of us have been wondering. makes sense why i keep seeing repeat villagers too, it has to be rolling species first.

Others are onto random move ins (i. e. letting the plot fill up) are influenced by lacking a personality whereas mystery islands are definitely not. If you're lacking a smug, the chances for Raymond to be a random move in are higher than if you went on mystery islands for him, so I would suggest trying the random move in strategy for him...
 
I believe early game it preferentially rolls villagers of personality types you don't have yet. This may explain why there were 12 instances of octopus villagers, as opposed to 9 as predicted.
idk sample size, but if jocks and uchi are seen to be less common than the rest (potentially barring smug being less than jock as it's a significantly smaller pool), that'd be a good indicator here for a large team effort, as no matter how many people contribute, we all started with those 2 personalities.

def the case on random move ins at least (as mentioned); but when I was only missing cranky and snooty, I found about half of the countless islands I visited that night gave me cranky and snooty villagers.
 
Others are onto random move ins (i. e. letting the plot fill up) are influenced by lacking a personality whereas mystery islands are definitely not. If you're lacking a smug, the chances for Raymond to be a random move in are higher than if you went on mystery islands for him, so I would suggest trying the random move in strategy for him...
It seems island hopping is my only option for Raymond because I got two smug villagers already. 😂
 
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