  
| Author: | Teup  | | Posted: | Oct 1, 2018 09:05 | | Subject: | Re: 90-percentile as new average price ? | | Viewed: | 78 times | | Topic: | Suggestions | |
|
| In Suggestions, Gaston.La.Brick writes:
| | I noticed the highest prices of items sold (or of items that are on sale), have
an out of proportion influence on the average prices.
Example: when 9 people sell (or have sold) an item at €0.10 but 1 person has
sold that item for €10.00, the average price would be €1.09
You may say this example is not realistic, but it's not that unrealistic
either. Check out item 6558. The avg used price of last 6 month sales is €0.023,
while the majority of the sales are for less as €0.02
If you look more closesly, you see a few sales at a high price, but not a lot.
(Note: someone even sold a few of these for €1.00 !)
It's my suggestion to change the calculation of avg price to use the 90-percentile
method. So only the 90 percent (lowest prices) are taken into account. That way,
the top 10-percent highest prices are not taken into account when calculating
the avg price.
To avoid weird behaviours, the rule could be in place only when there are 10
items sold/for sale.
Example would become an avg price of €0.10
Another somewhat more complex method would be the use the median. Not the mathematic
average, but the middle price: 50% of the sellers have a lower price, 50% of
the sellers have a higher price.
What do you guys think?
|
This suggestion comes up now and then, I am not in favour, as it makes the priceguide
less transparent but most of all it promotes the race to the bottom even more.
In a different kind of design, with a different role and usage for the priceguide,
I could be in favour. But the way Bricklink is set up now, I think sellers very
strongly evaluated based on their prices not being above average - at least that's
how I used to use Bricklink when I was a buyer. I think in the current design,
we need those quirky up-effects, not because they make for the most ideal and
scientifically sound kind of priceguide, but to balance things in a context where
down-effect already prevails.
What surprises me though is that you suggest it to include only the lowest. Why
not middle 90%? What you propose seems to me like a race to the bottom on top
of a race to the bottom.. That sounds like you prefer the priceguide showing
just low prices over accurate prices. I really don't think prices on Bricklink
are unfair at all considering all the work that goes into running a store.
|
|
Message is in Reply To:  90-percentile as new average price ? - Gaston.La.Brick (1842) | I noticed the highest prices of items sold (or of items that are on sale), have an out of proportion influence on the average prices. Example: when 9 people sell (or [...]
(69 months ago, Oct 1, 2018, to Suggestions) |
Message Has 2 Replies: | Re: 90-percentile as new average price ? - Gaston.La.Brick (1842) | [...] You are jumping to conclusions. I never said prices are unfair. I'm saying the average calculation, although mathematically correct, is not a good indication of what [...]
(69 months ago, Oct 1, 2018, to Suggestions) |
Re: 90-percentile as new average price ? - Bricks_NW_UK (1367) | I agree with the point Teup makes on this. "The race to the bottom" is something that concerns us as well. Constant "sales" just harm the overall selling prices. Same goes with [...]
(69 months ago, Oct 1, 2018, to Suggestions) |
8 Messages in this Thread: Msg 1 - Gaston.La.Brick (1842) 69 months ago Oct 1, 2018 to Suggestions
 Msg 2 « - Teup (6610) 69 months ago Oct 1, 2018 to Suggestions
 Msg 3 - Gaston.La.Brick (1842) 69 months ago Oct 1, 2018 to Suggestions
Msg 4 - MidwestBrick (1855) 69 months ago Oct 1, 2018 to Suggestions
 Msg 5 - yorbrick (1185) 69 months ago Oct 1, 2018 to Suggestions
Msg 6 - Bricks_NW_UK (1367) 69 months ago Oct 1, 2018 to Suggestions
Msg 7 - Etown (1740) 69 months ago Oct 1, 2018 to Suggestions
Msg 8 - jx (13) 46 months ago Aug 12, 2020 to Suggestions
Entire thread on one page
This message and all its replies on one page
|
|
Netherlands, Utrecht
