Value calculation - the final algorithm?

Dear all,

I wonder how the calculation of the values finally work.
Below in italic is my original suggestion for the implementation of values, back in 2015: https://en.numista.com/forum/topic44962.html

My questions are:
1) Is this how it finally works? i.e. what is the concrete algorythm?
2) How do we handle extremes?
I think we have a lot extreme valuations (or misvaluations, if there is such a word) in both directions. Let me give 2 examples: a currently circulating euro 20 cents is valued for 13 eurocents in a case. (I would love to know the source and buy 100000 of those. ), while Krause quotes for a gold 5 ruble of 1907 USD4000,- which is either nonsense or I shall buy a yacht, soon)
3) Is there a tool for referees for make adjustments? (I currently do not see them)

Thanks for the answers.

The original idea:
1) VALUE CELLS.
On the coin page, to the right of the "personal comment" icon, add 5 additional cells, which accept only numeric value in an 123.12 format; these would be respectively: VG value, F value, VF value, XF value, UNC value. Here people can enter the estimated value of their coins.
This is a private cell, only the owner can see it, the owner can modify it, so it is your value!

2) CALCULATION OF VALUE.
if you enter data, the total value can be simply calculated by multiplying the respective grade values with the number of coins you have in the respective grade.

3)TOTAL VALUES.
In my suggestion, you can see the total value on 3 levels:
1. on the coin page; the total value of the type of coin
2. on the 'your coins' page by country, so you see the value of your French collection
3. on the dashboard, the total value of your entire collection

This will make quite a few people happy.

My suggestion goes further.
If enough people (my vote will go for 10) add a value to a given cell, the value shall become a public Numista value.

The calculation method have to consider the idiots who overvalue their coins, and those who undervalue as well, so the highest 30% and the lowest 20% shall be ignored, and the average of the rest shall become a Numista value.

This value could appear in all users private cells, as a suggestion, which of course the user can overwrite, and add his/her own estimate; with that also contributing to the Numista value, hence making it a dynamic number over time.

Needless to say these Numista values will not be in any way mandatory to accept in a swap or so, but it will be maybe a better indicator on the long run, than Krause.

Hello Imreh,

Here are the rules for calculation.

1. Values are computed by type, year/variety and grade
   
2. A value is calculated only if at least 4 users entered a price for their coin
   
3. The value is calculated as the median of the values entered by the users
   
4. If a user entered several values, a median of his values is calculated and only the resulting value is used for the median calculation of step 3.
   
5. Calculations are done in euro. Values entered by the users are converted in euro at the time they are entered. The display of the calculated value is converted to the user's currency at display time.
   

Values calculated by Numista are publicly displayed on the coin page.
Values entered by each user are visible only to themselves, on all the pages where they can see their coins.

Users can see the total value of their collection, based on 2 different calculations:

1. Based on their own value (sum of quantity x the value they entered)
   
2. Based on the value calculated by Numista (sum of quantity x the value as described above)
   

Future planned improvements are:

• Take data also from real online sales (e.g. eBay, auction houses)
  
• Take into account inflation
  

Referees and admins have no way to adjust the values manually.

Thanks, Xavier, sounds very good.
I am experiencing it currently, so probably I will have some thoughts on this.
Right now, only one thing comes to mind:

If we have circulating currencies, would that be difficult to build in an algorithm - linking to an exchange site - that automatically calculates a realistic value?
ex1: a circulating 20 eurocents coin shall be 20 eurocents in whatever currency I am choosing to view.
ex2: a circulating 100 forint coin (in whatever grade) shall be EUR 0,31 today:
https://www.xe.com/currencyconverter/convert/?Amount=100&From=HUF&To=EUR

What do you think?

p.s. congratulaions for the improvements, great job!

EDIT: A clarifying question: So, on the "My coins" page, the "the estimate for 29% of my coins" - means that 29% of my coins have a calculated value, and based on that, the calculation is made? Is that correct?

Thanks Imreh for your feedback.

Converted value is already shown in the "Features" box, next to the face value, for coins that are not demonetized.
Examples
https://en.numista.com/catalogue/pieces10969.html
https://en.numista.com/catalogue/pieces28731.html

I'm not convinced the collection value should always be equal to the face value. For instance, if I find a regular euro coin from Vatican, I would not give it for the face value.

Replying to your last question, it would indeed mean that only 29% of your coins have a value, and the value of those coins (29% of your collection) is shown.

ok. thanks for the info.

Quote: "Xavier"​
​I'm not convinced the collection value should always be equal to the face value. For instance, if I find a regular euro coin from Vatican, I would not give it for the face value.

​The face value should be the minimum value for any grade.

Quote: "Cerulean"​

Quote: "Xavier"​
​​I'm not convinced the collection value should always be equal to the face value. For instance, if I find a regular euro coin from Vatican, I would not give it for the face value.
​
​

​​The face value should be the minimum value for any grade.

Only if they are still circulating : when demonetized, the face value worth nothing.

For example, the face value of a 10 FRF was about 1,52€ in 1999, however this coin worth almost nothing now (we can get one for few cents in France) : https://en.numista.com/catalogue/pieces9.html

Hi
Why is it only possible to add and edit "Buying value" in swap pages and not also on the coin page itself?

Thanks...

Quote: "Cycnos"​

Quote: "Cerulean"​
​

Quote: "Xavier"​
​​​I'm not convinced the collection value should always be equal to the face value. For instance, if I find a regular euro coin from Vatican, I would not give it for the face value.
​​
​​

​​​The face value should be the minimum value for any grade.

​Only if they are still circulating : when demonetized, the face value worth nothing.
​
​For example, the face value of a 10 FRF was about 1,52€ in 1999, however this coin worth almost nothing now (we can get one for few cents in France) : https://en.numista.com/catalogue/pieces9.html

​+1

Quote: "mikimaus"​Hi
​Why is it only possible to add and edit "Buying value" in swap pages and not also on the coin page itself?
​
​Thanks...

​You need the new collection management to be able to enter a value. You can activate it on your settings page by checking the first option for "Display of my collection".
Only the swap page doesn't have the old collection management, so the new one is activated there independently of your selection.

Many thanks! Though I find it "hard" to find something like this on myself. Maybe it would be suitable if this functionality would be available on each coin page - "switch on" and "switch off" like, for easier handling. I just still like "old" interface better.