Coin and grade value averages.

Hi. While I like the new addition of average coin values to the site, do you think that using a median average really is the best way to do it? For example if a grade of coin has one very low valuation and one very high valuation the median value is never going to change, no matter how many other values are added even if most are at one end of the scale. However if a mean or even a mode average was used I think you'd see a more representative value of the majority of coins.
An example might clarify my point.....
If a coin had four values, 0.1, 0.9, 0.9 and 1.0 then the median would be 0.55, the mode would be 0.9 and the mean would be 0.6. If another coin was added with a value of 0.8, the median would stay the same, but the mean would change to 0.75; closer to the value of most of the coins (the mode would stay the same at 0.9 as more coins had that value than any other).
I hope that helps (and that my maths is right) but hopefully you see the point.

I heard the lowest as well as they highest value added for a same coin, year line and grade are not counted so in your first example it would be 0.9

Citeer: "apuking"​I heard the lowest as well as they highest value added for a same coin, year line and grade are not counted so in your first example it would be 0.9

​Oh, I hadn't heard of that being the case, but even so the principle point still stands. It would only take two very low values and two very high to get round that.

As far as I know, the median is indeed used with ALL values. But I think your definition seems to be off, as the median is kind of the middle value, in your example 0,9.
https://en.m.wikipedia.org/wiki/Median

So the numerical values of the highest or lowest values are indeed not used in the calculation, but do help to decide what the middle value is. In my opinion an acceptable way to go.

Citeer: "BramVB"​As far as I know, the median is indeed used with ALL values. But I think your definition seems to be off, as the median is kind of the middle value, in your example 0,9.
​https://en.m.wikipedia.org/wiki/Median
​
​So the numerical values of the highest or lowest values are indeed not used in the calculation, but do help to decide what the middle value is. In my opinion an acceptable way to go.

​Perhaps my memory from school was off then. I remembered it as being the half way point between the highest and the lowest.

I confirm the values are computed using median values, as defined in the Wikipedia link posted above.
So if people added values 0.1, 0.9, 0.9 and 1.0, Numista would show 0.9.
If another coin was added with a value of 0.8, Numista would still show 0.9.
If yet another coin was added with a value of 0.8, Numista would show 0.85.

Thanks for clarifying that Xavier. The problem has obviously been with my memory of the definition of a median value from my school days. In my defence it was over 30 years ago and my memory isn't what it was.