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| | | Author: | ToriHada  | | Posted: | Oct 17, 2010 10:42 | | Subject: | Remove hi/lo prices from Price Guide | | Viewed: | 283 times | | Topic: | Suggestions | | Status: | Open | | Vote: | [Yes|No] | |
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| Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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| | | | | Author: | Rob_and_Shelagh | | Posted: | Oct 17, 2010 10:49 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 40 times | | Topic: | Suggestions | |
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| In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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Do you mean that each member could set his own criteria for the average price
in the guide? i.e. some would choose to calculate an average with the extremes
included and some would not? The result displayed would therefore be different
on different users screens?
Robert
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| | | | | | | Author: | ToriHada | | Posted: | Oct 17, 2010 10:58 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 47 times | | Topic: | Suggestions | |
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| In Suggestions, Rob_and_Shelagh writes:
| | Do you mean that each member could set his own criteria for the average price
in the guide? i.e. some would choose to calculate an average with the extremes
included and some would not? The result displayed would therefore be different
on different users screens?
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Yes, exactly. And before you talk about buyer confusion, keep in mind that Price
Guide results can already be customized and tweaked in mulitple differents ways
for each member. See your own settings page for displaying Price Guide results:
http://www.bricklink.com/priceGuideSettings.asp
Via this page, each member can already tweak how they view the Price Guide and
what data can be included or excluded by, for example, excluding listings for
incomplete sets and excluding listings for entire countries and regions.
Thor
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| | | | | | | | | Author: | Rob_and_Shelagh | | Posted: | Oct 17, 2010 11:01 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 36 times | | Topic: | Suggestions | |
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| In Suggestions, fosterbengoshi writes:
| | In Suggestions, Rob_and_Shelagh writes:
| | Do you mean that each member could set his own criteria for the average price
in the guide? i.e. some would choose to calculate an average with the extremes
included and some would not? The result displayed would therefore be different
on different users screens?
|
Yes, exactly. And before you talk about buyer confusion, keep in mind that Price
Guide results can already be customized and tweaked in mulitple differents ways
for each member. See your own settings page for displaying Price Guide results:
http://www.bricklink.com/priceGuideSettings.asp
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No, I agree! I just wanted clafication.
| | Via this page, each member can already tweak how they view the Price Guide and
what data can be included or excluded by, for example, excluding listings for
incomplete sets and excluding listings for entire countries and regions.
Thor
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I actually prefer this option to having "my" price guide tweeked forcibly as
if it is assumed I cannot interpret the data for myself.
So it's a yes from me although I fear it might be more resource hungry than the
big brother approach.
Robert
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| | | | | Author: | Reki_Lobsheek | | Posted: | Oct 17, 2010 12:10 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 36 times | | Topic: | Suggestions | |
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| voted yes
I think it's a great idea; would have even voted yes if the proposal was for
making this a standard for the price guide in general
Reki
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| | | | | Author: | brickmover | | Posted: | Oct 17, 2010 13:33 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 34 times | | Topic: | Suggestions | |
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| In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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I think this would be really cool. Voted yes, but not because it is cool. I'll
explain.
First off, I think it is important that including/excluding some portion of the
extreme values would be "just another" non-default option along with the rest
of the already existing customizable personal price guide options.
I find it frustrating that, as has been mentioned, we are given a very limited
way of looking at highly aggregated data. It would be nice to be able to determine
for ourselves how we want to view the price guide.
There are serious disadvantages to this option and reasons I would vote no. One
major drawback to trimming high and low values is that it can be very difficult
to make practical use of. For instance, if BrickLink only offered a single part,
it would be easy to look at the price data and say "you know, I think I want
to ignore the upper and lower 5% of listings." But for the next part that particular
arbitrary cutoff might not be ideal and you might want to go with 10%. This is
a huge deal. For this to "work" on so many different items, you really do need
to do it completely ad hoc. Look at the data for a part, determine what percent
of prices you want to ignore, set your price guide settings accordingly, but
then wonder if you need to revisit the whole process and change your settings
for the next part you look at. Not practical.
For every part that it gives you more accurate information on, there may be other
parts where you are trimming information you'd prefer to keep. This could actually
be the case for many parts, since many parts in the price guide do NOT need any
trimming- you'd be throwing out good data.
On the surface this doesn't sound like a problem, but what about all those lots
that are rare expensive parts available on BL in a very small number of stores?
I can't think of a lot of parts where I don't want to ignore any prices. And
it would be a pain to keep changing my price guide setting for extreme value
trimming on and off.
Also, there are many parts for which only a small number of lots are available
on BL. When you go to lop off some percent of the price listings, there has to
be a standard formula for deciding how to round up or down. If you go with 5%
off the top and bottom, what if you only have 10 listings? Do the first and last
get excluded or not? Each would be 10% of the data, but do you start counting
before or after the first or last lot? Does one get removed but not the other,
and if so, which one, the high price or the low price? Do no prices get removed
unless the number of lots available are above a certain threshold?
It sounds simple on the surface but it can actually be very complicated. I regularly
switch back and forth between different software at work that are programmed
with completely different definitions for how to make various quantiles from
a set of values. There is no official universal agreement on how to define the
cut points for some percent of data in a list. This would especially be a problem
for parts that have few lots available. I think a lot of people who might use
this feature could be trading in one statisitc for the price data (the regular
average) which they at least KNOW is obscuring information, for another measure
which they may not even be aware of what good information they may be losing.
Another thing is that trimming upper and lower values (equally on each end)-
the more you trim the closer you get to simply settling on the median. Why stop
halfway. Just proceed straight to the median, where all the data above and below
the middle one are trimmed. This is more easily interpretable for people and
less problematic in regards to all the stuff mentioned above.
And what if someone only wants to trim high prices and not low prices? Is that
an option? Or are they restricted to trimming both equally? I think that is a
bad restriction because there are a lot more legit, competitive low prices that
one might not want to trim compared to the crazy high prices that are much more
influential on the average price and which sellers do not need to take into account
as far as competition goes.
Now returning full circle to why I actually vote yes. Although I would love the
ability to set an arbitrary quantile, such as upper or lower 5%, 25%, 90%, heck
37% of prices, I strongly feel we will never be given this option. Call me cynical
but I believe there are plenty of people here who make good money on BL and would
never want to see the power to disaggregate price guide data at everyone else's
fingertips. Whether or not is it true, the argument would be made that it would
make the whole site more competitive and prices would drop in general. People
fear that competition. BL is a business run by someone right? Well, if I were
that person it would be clear to me that it is beneficial for the business to
keep plenty of price data in an aggregated, relatively inaccessible form, such
as offering "averages". Lame. I laugh every time I see the "statistics" page
on this site. The data are SO aggregated they are pretty much useless. I don't
think that will change much with the price guide data. I'm sure plenty of people
will vote no on this (secretly). So I vote yes so as not to contribute to that
and because I am curious as to those results lol.
If we had a quantile price setting like:
5% of prices under: x.xx
50 % of prices (median) under: x.xx
95% of prices under: x.xx
for example, and if those cutoffs could be customized, or if it could be set
to display as many as you are interested in, that would be powerful information.
I like it. But I don't think we will ever be given access to that kind of information.
So I cut my losses and hope for the median only, as a concession.
This is a cool suggestion, but I expect it will get knocked down. I just wish
my reasons for thinking so weren't so cynical haha. Whoa, that's enough forum
posting to last me a while. Where does the time go.
Matt
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| | | | | Author: | leggodtshop | | Posted: | Oct 17, 2010 14:06 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 25 times | | Topic: | Suggestions | |
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| Voted YES of course. It is normal statistics procedure to remove hi/lo values
from large enough ranges of numbers to obtain a better average. It does not work
for small ranges, so there should be e.g. at least X values available to remove
hi/lo values. (X = 10, X = 100  )
Arnoud
In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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| | | | | Author: | Rolf | | Posted: | Oct 17, 2010 15:49 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 25 times | | Topic: | Suggestions | |
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| In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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Yes, please!!!
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| | | | | Author: | beelzibus | | Posted: | Oct 17, 2010 15:58 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 26 times | | Topic: | Suggestions | |
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| In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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Yes IMO it's a no brainer.
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| | | | | Author: | Lonely_Brick_OH | | Posted: | Oct 17, 2010 18:35 | | Subject: | (Cancelled) | | Viewed: | 29 times | | Topic: | Suggestions | |
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| | (Cancelled) |
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| | | | | Author: | nhardee | | Posted: | Oct 27, 2012 21:58 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 94 times | | Topic: | Suggestions | |
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| I would really like the median price.
thanks
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| | | | | Author: | change | | Posted: | Oct 27, 2012 22:04 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 89 times | | Topic: | Suggestions | |
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| In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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Welcome back!
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| | | | | | | Author: | goshe7 | | Posted: | Oct 27, 2012 22:28 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 76 times | | Topic: | Suggestions | |
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| In Suggestions, change writes:
| | In Suggestions, fosterbengoshi writes:
| | Please implement an OPTION to allow members to have the highest and lowest prices
removed when calculating Price Guide averages for any items with ten or more
Price Guide entries. The purpose of this suggestion is to prevent most extreme
pricing anomalies from corrupting and distorting Price Guide averages - averages
which many sellers use to price their goods and decide which sets to purchase
and part out.
Removing these extreme data points is a long proven statistical tool for improving
the accuracy of averaging.
This suggestion is offered in conjunction with or as an alternative to the currently
pending suggestion to incorporate median prices in the Price Guide. Personally,
I don't care which of these two suggestions are implemented. I just hope at least
one of them is implemented soon. Whatever is easiest and best in Admin's opinion.
Thor
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Welcome back!
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You would think that 25 months would be the oldest suggestion... But you would
be mistaken. However, the honor of that distinction is still directed to the
right person. 
http://www.bricklink.com/message.asp?ID=435580
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| | | | | | | | | Author: | nhardee | | Posted: | Oct 30, 2012 08:38 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 43 times | | Topic: | Suggestions | |
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| !
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You would think that 25 months would be the oldest suggestion... But you would
be mistaken. However, the honor of that distinction is still directed to the
right person.
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Wow that is embarassing, I usually check the date before posting.
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| | | | | | | | | | | Author: | Brettj666 | | Posted: | Oct 30, 2012 08:51 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 51 times | | Topic: | Suggestions | |
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| In Suggestions, nhardee writes:
| | !
| |
You would think that 25 months would be the oldest suggestion... But you would
be mistaken. However, the honor of that distinction is still directed to the
right person.
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Wow that is embarassing, I usually check the date before posting.
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It probably gave Foster a laugh though
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| | | | | | | Author: | tEoS | | Posted: | Oct 27, 2012 22:29 | | Subject: | Re: Remove hi/lo prices from Price Guide | | Viewed: | 92 times | | Topic: | Suggestions | |
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| He's not back.
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USA, North Carolina
United Kingdom, England
Belgium, Brussels
Netherlands, Overijssel
Canada, Ontario
