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Taulipang
Joined: 15-Apr-2017
Posts: 13
I am trying to get a feel for how this numbers compare to each other, ever though I know they are based on this site. Like 10 vs 20 vs 40 vs 75. So far it seems like my rarer coins fall 35-60 and I am not sure if that means they are rarer or not. Today I found a coin with an index of 86. Just trying to get a feel for comparing the rarity of coins in my own collection
thank you
MonaSeaclaid
Joined: 21-Jan-2016
Posts: 991
The highest is 100 and I believe that means only one or maybe two people on the site have it.
neilithic
Joined: 28-Mar-2011
Posts: 7494
100 means nobody has it, as soon as someone lists it in their collection it drops to 97, then 95 with another person listing it

I am the referee for NZ and we get the numbers of how many members own each coin, so I can give you a rough idea of a range or rarity ratings

rarity rating 15 - around 1000 members
rarity rating 21 - around 570 members
rarity rating 26 - around 380 members
rarity rating 35 - 185 members
rarity rating 40 - 145 members
rarity rating 53 - 85 members
rarity rating 81 - 21 members
rarity rating 90 - 8 members
rarity rating 93 - 4 members
AmerSalmeh Numista team
Joined: 29-Jul-2014
Posts: 1377
Quote: "MonaSeaclaid"​The highest is 100 and I believe that means only one or maybe two people on the site have it.
I'm afraid you are wrong.

​100 means no one
https://en.numista.com/catalogue/pieces74086.html

next is 97 which is 1 owner
https://en.numista.com/catalogue/pieces93748.html

then 95 for 2 owners
https://en.numista.com/catalogue/pieces64643.html

94 for 3 owners
https://en.numista.com/catalogue/pieces83643.html

and so on.
Catalog Master Referee & Referee for most Arab countries
https://www.instagram.com/amer.coins
Amer Salmeh
MonaSeaclaid
Joined: 21-Jan-2016
Posts: 991
No need to pile on, it was an honest mistake.

I appreciate the detailed information. :)
Taulipang
Joined: 15-Apr-2017
Posts: 13
wow thank you, this gives me a much better idea, I can create some percentiles and such
Taulipang
Joined: 15-Apr-2017
Posts: 13
It seems like 4 is typically the most common of coins (although I think I saw a 3). Perhaps these numbers can be used to create a rarity rating for a whole collection. I just like the idea of comparing different coins and collections. Especially since rarity does not translate to value with foreign coins often
AmerSalmeh Numista team
Joined: 29-Jul-2014
Posts: 1377
Quote: "MonaSeaclaid"​No need to pile on, it was an honest mistake.

​I appreciate the detailed information. :)
​I was just explaining - sorry didn't mean to 0:)
Catalog Master Referee & Referee for most Arab countries
https://www.instagram.com/amer.coins
Amer Salmeh
MonaSeaclaid
Joined: 21-Jan-2016
Posts: 991
It just shows how little understood the system is, really. I've been an active member here for over a year and I was an unregistered skulker for a long time before that and that was all I could really get from it. And I took particular interest whenever it was discussed.
AmerSalmeh Numista team
Joined: 29-Jul-2014
Posts: 1377
Probably since you didn't try adding coins.
Once you add a new coin you purchased, you will notice rarity is 100, and once you tick it as you own it, you'd notice it became 97. That's how it started with me to know how the system works
Catalog Master Referee & Referee for most Arab countries
https://www.instagram.com/amer.coins
Amer Salmeh
neilithic
Joined: 28-Mar-2011
Posts: 7494
It's not a very useful tool, the only thing it's really useful for is to see what coins are likely to be popular to put in your swap list. I think a while ago Phil suggested that we switch to the universal rarity scale, which sounded quite good to me

https://www.providentmetals.com/knowledge-center/collectible-coins/universal-rarity-scale.html
MonaSeaclaid
Joined: 21-Jan-2016
Posts: 991
Quote: "AmerSalmeh"​Probably since you didn't try adding coins.
​Once you add a new coin you purchased, you will notice rarity is 100, and once you tick it as you own it, you'd notice it became 97. That's how it started with me to know how the system works
​That would require me to have an uncommon coin. :O

It may not be a useful tool, but it's an interesting one. I also like the idea of using the Universal scale too though.
Stupendousman35
Joined: 31-Jul-2016
Posts: 61
Quote: "neilithic"​It's not a very useful tool, the only thing it's really useful for is to see what coins are likely to be popular to put in your swap list. I think a while ago Phil suggested that we switch to the universal rarity scale, which sounded quite good to me

https://www.providentmetals.com/knowledge-center/collectible-coins/universal-rarity-scale.html
​that scale would be interesting to see implemented!
Taulipang
Joined: 15-Apr-2017
Posts: 13
That looks like a good option. Expecially if they could add it for the type of coin and the individual coin/strike
tony.c
Joined: 27-Feb-2010
Posts: 710
I think NRI has no use at all, especially for coins that have been struck many consecutive years : some years can be really scarce, while others are very common, but NRI will be an index for the coin type... It just gives you an idea on how many members own that type of coin.
Greetings
Tony
BryanJ
Joined: 31-Dec-2015
Posts: 389
Thanks for the info, Neil. From looking at the rarity index I had decided that below 20 were really, really common coins, and above 40-50 they were starting to get relatively rare. It seems even coins with as low an index as 26 are not that common (or, more accurately, commonly owned by Numista members). Time to rework the formula to use the percentage, not an absolute number, of members owning the coin.
ken6528
Joined: 11-Sep-2009
Posts: 1104
There is something else figured into the rarity rating. These numbers are from some Fiji coins.

rarity rating 24 - 413 members
rarity rating 23 - 399 members
rarity rating 22 - 344 members

These number are going the wrong way.
Numista referee for British Antarctic Territory, British Indian Ocean Territory, United States, Fiji, Cook Islands, Philippines, Vanuatu
AmerSalmeh Numista team
Joined: 29-Jul-2014
Posts: 1377
Quote: "ken6528"​There is something else figured into the rarity rating. These numbers are from some Fiji coins.

​rarity rating 24 - 413 members
​rarity rating 23 - 399 members
​rarity rating 22 - 344 members

​These number are going the wrong way.
​has to do probably with number of year lines for each
Catalog Master Referee & Referee for most Arab countries
https://www.instagram.com/amer.coins
Amer Salmeh
Idolenz
Joined: 13-Jul-2013
Posts: 1977
Do these numbers come from coins with more than one year line?
Because the NRI is mostly influenced by unique member count, but maybe something else because when I checked all the one year line coins I could look up I sometimes got different NRI values for the same member count (X members got Y, the other time X members got Z).

(the graph is not the most accurate because of the relative small amount of single year coins I could check)
              
ken6528
Joined: 11-Sep-2009
Posts: 1104
number of year lines are backwards too.
Here are the coins all from Fiji
rarity rating 24 - 413 members KM# 7
rarity rating 23 - 399 members KM# 2
rarity rating 22 - 344 members KM# 20
Numista referee for British Antarctic Territory, British Indian Ocean Territory, United States, Fiji, Cook Islands, Philippines, Vanuatu
AmerSalmeh Numista team
Joined: 29-Jul-2014
Posts: 1377
Maybe has to do with number of unique owners or number of year lines

for example:
https://en.numista.com/catalogue/pieces89945.html
this medal has 2 year lines and I'm the only one who owns both years.
so in total you can say 2 members own this, still rarity of 97
Catalog Master Referee & Referee for most Arab countries
https://www.instagram.com/amer.coins
Amer Salmeh
ken6528
Joined: 11-Sep-2009
Posts: 1104
Quote: "AmerSalmeh"​Maybe has to do with number of unique owners or number of year lines

​for example:
https://en.numista.com/catalogue/pieces89945.html
​this medal has 2 year lines and I'm the only one who owns both years.
​so in total you can say 2 members own this, still rarity of 97
​I would think the odds of that happening would even out with 400 people owning the coin.
Numista referee for British Antarctic Territory, British Indian Ocean Territory, United States, Fiji, Cook Islands, Philippines, Vanuatu
Taulipang
Joined: 15-Apr-2017
Posts: 13
Quote: "ken6528"
Quote: "AmerSalmeh"​Maybe has to do with number of unique owners or number of year lines
​​
​​for example:
​​https://en.numista.com/catalogue/pieces89945.html
​​this medal has 2 year lines and I'm the only one who owns both years.
​​so in total you can say 2 members own this, still rarity of 97
​​I would think the odds of that happening would even out with 400 people owning the coin.
It would not likely even out if the mintage varied greatly between years​
eudald
Joined: 19-Nov-2013
Posts: 1
Hi,

I was curious about the formula and I’ve done some math to approximate it based on the data provided in the forums and should be something close to the following:

Rarity = 3200 / ( 32 + x ^ 0.75)

where "x" is the number of user that own a coin of this type.

The data I recollected is ( users with the coin , rarity):

(0,100)
(1,97)
(2,95)
(8,90)
(60,60)
(100,48)
(1000,15)

cheers
halfdisme
Joined: 6-Oct-2017
Posts: 613
Quote: "MonaSeaclaid"​The highest is 100 and I believe that means only one or maybe two people on the site have it.
​To be absolutely accurate, a rating of 100 just means that no member has REPORTED owning any date of that specific type of coin.

If you have a rare date of a specific type, the rarity rating will only reflect the number of coins REPORTED for that entire type, including all the common dates.

Some members have stated that they do not post their collections. Others have not finished posting what they have.
CassTaylor
Joined: 30-May-2014
Posts: 6481
Quote: "halfdisme"
​If you have a rare date of a specific type, the rarity rating will only reflect the number of coins REPORTED for that entire type, including all the common dates.
That's precisely why I'd advocate for each year line to have its own NRI, if we're going to keep it around. It's awfully misleading for new members as it is....

I actually went and started a suggestion for it! :wiz:
Une Franglaise; ♪ je brosse ma chevelure ♫
yvon
Joined: 9-Jun-2017
Posts: 249
Quote: "CassTaylor"
Quote: "halfdisme"​​
​​If you have a rare date of a specific type, the rarity rating will only reflect the number of coins REPORTED for that entire type, including all the common dates.
​​
​That's precisely why I'd advocate for each year line to have its own NRI, if we're going to keep it around. It's awfully misleading for new members as it is....

​I actually went and started a suggestion for it! :wiz:
​That would be a real improvement!
...you can run,  but you can't hide...
Monninen1
Joined: 23-Oct-2017
Posts: 902
Quote: "AmerSalmeh"
Quote: "MonaSeaclaid"​The highest is 100 and I believe that means only one or maybe two people on the site have it.
​I'm afraid you are wrong.

​​100 means no one
https://en.numista.com/catalogue/pieces74086.html

​next is 97 which is 1 owner
https://en.numista.com/catalogue/pieces93748.html

​then 95 for 2 owners
https://en.numista.com/catalogue/pieces64643.html

​94 for 3 owners
https://en.numista.com/catalogue/pieces83643.html

​and so on.
​you need to change that example, now someone on numista has that 2 Kharub
halfdisme
Joined: 6-Oct-2017
Posts: 613
Does the Rarity Index reflect the entire Numista membership??

It is hard to believe that there are so many coins that are not reported by any member (100), or have only been reported by one member (97), out of a membership of over 95,000 collectors!
Cycnos
Joined: 22-Apr-2017
Posts: 1810
Quote: "AmerSalmeh"​Maybe has to do with number of unique owners or number of year lines

​for example:
https://en.numista.com/catalogue/pieces89945.html
​this medal has 2 year lines and I'm the only one who owns both years.
​so in total you can say 2 members own this, still rarity of 97
​Yep, it's influence by the number of users who owns the coin, not the total amount of coins in the member collections.

I have four identical coins but the page still shows a rarity index of 97 (even if I keep them all in my collection) : https://fr.numista.com/catalogue/pieces149752.html

I think the rarity index uses a function based on the number of users who have at least one of this coin in their collection.
Quote: "halfdisme"​Does the Rarity Index reflect the entire Numista membership??

​It is hard to believe that there are so many coins that are not reported by any member (100), or have only been reported by one member (97), out of a membership of over 95,000 collectors!
I don't have difficulties to buy coins that are not listed on the catalog so I presume it's not hard to find coins with a NRI 97 or 100 on numista.

We should keep in mind that only a portion of the worldwide collectors are present on this website and we are a minority to have enter our whole collection here.

Some coins are barely collected (too expensive, unknown from the majority of collectors, they don't interest anyone...), can't be found easily because of their rarity or can be seen in museums only.
CassTaylor
Joined: 30-May-2014
Posts: 6481
Quote: "Cycnos"
​We should keep in mind that only a portion of the worldwide collectors are present on this website and we are a minority to have enter our whole collection here.

​Some coins are barely collected (too expensive, unknown from the majority of collectors, they don't interest anyone...), can't be found easily because of their rarity or can be seen in museums only.


​And of course, even out of that portion of collectors that are both on the site and active users of it (for their collection, not necessarily the forum), some haven't finished/don't bother/want to record their collections on here, so there's that to factor in as well.
Une Franglaise; ♪ je brosse ma chevelure ♫
January First-of-May
Joined: 10-Apr-2016
Posts: 623
Quote: "CassTaylor"
Quote: "Cycnos"
​​We should keep in mind that only a portion of the worldwide collectors are present on this website and we are a minority to have enter our whole collection here.
​​
​​Some coins are barely collected (too expensive, unknown from the majority of collectors, they don't interest anyone...), can't be found easily because of their rarity or can be seen in museums only.
​​
​​
​​
​​And of course, even out of that portion of collectors that are both on the site and active users of it (for their collection, not necessarily the forum), some haven't finished/don't bother/want to record their collections on here, so there's that to factor in as well.
​In my case in particular, when I discover that a coin in my collection (usually ancient or medieval, but occasionally just 17th century Polish) is not listed on Numista, I usually don't bother to add it (especially if it's 17th century Polish, because that section has its own weird standards), and only very rarely check in to see if it had since been added.
So I won't be surprised if there's a bunch of coin types on Numista that I actually have but hadn't entered because back when I was entering that part of my collection those types hadn't been added yet.

(Probably not very many, admittedly; and I did end up entering most of the coins that I remembered distinctively rather than as "yet another random ancient".)
agoodman
Joined: 29-Jan-2018
Posts: 13
Quote: "halfdisme"​Does the Rarity Index reflect the entire Numista membership??

​It is hard to believe that there are so many coins that are not reported by any member (100), or have only been reported by one member (97), out of a membership of over 95,000 collectors!
Just for fun, I have 2 of these in my collection, but I am pretty sure at least one other member also has at least one because a couple days after I aded it it dropped from 99/100 to 97: https://en.numista.com/catalogue/pieces145167.html

I only have one of these in my collection, but I do have one and the NRI is still 100: https://en.numista.com/catalogue/pieces135262.html
Cycnos
Joined: 22-Apr-2017
Posts: 1810
Quote: "agoodman"
Quote: "halfdisme"​Does the Rarity Index reflect the entire Numista membership??
​​
​​It is hard to believe that there are so many coins that are not reported by any member (100), or have only been reported by one member (97), out of a membership of over 95,000 collectors!
​Just for fun, I have 2 of these in my collection, but I am pretty sure at least one other member also has at least one because a couple days after I aded it it dropped from 99/100 to 97: https://en.numista.com/catalogue/pieces145167.html

​I only have one of these in my collection, but I do have one and the NRI is still 100: https://en.numista.com/catalogue/pieces135262.html
​NRI 97 : only one member has this coin in its collection. So you are the only one to have it here. NRI 99 is not possible on numista 8.

About the other coin, it's because this coin is not in your collection, but in your swap list (coins you own are not considered as part of your collection if you don't want to keep them).
NRI 100 : nobody has this coin in its collection.
agoodman
Joined: 29-Jan-2018
Posts: 13
Quote: "Cycnos"
​About the other coin, it's because this coin is not in your collection, but in your swap list (coins you own are not considered as part of your collection if you don't want to keep them).
​NRI 100 : nobody has this coin in its collection.
​Ah... That makes sense! :-)

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