Discussion Forum: Thread 360988

 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 12, 2024 08:06
 Subject: Why PG averages are useless
 Viewed: 264 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
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Store: Cosmic Toys
One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR
 


 Author: Andy_Bell View Messages Posted By Andy_Bell
 Posted: Aug 12, 2024 08:25
 Subject: Re: Why PG averages are useless
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 Topic: Price Guide
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Andy_Bell (2387)

Location:  USA, Alabama
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In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR

Using the sold averages - which is what people actually paid vs what people want
to sell for - eliminates some (but not all) of these error and anomolies.
 Author: StarBrick View Messages Posted By StarBrick
 Posted: Aug 12, 2024 08:44
 Subject: Re: Why PG averages are useless
 Viewed: 61 times
 Topic: Price Guide
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StarBrick (7172)

Location:  Netherlands, Gelderland
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That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.
 Author: peregrinator View Messages Posted By peregrinator
 Posted: Aug 12, 2024 08:50
 Subject: Re: Why PG averages are useless
 Viewed: 62 times
 Topic: Price Guide
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peregrinator (846)

Location:  USA, New Jersey
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In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

One easy way of mitigating this issue would be to remove both the highest and
lowest prices before calculating the average.
 Author: zorbanj View Messages Posted By zorbanj
 Posted: Aug 12, 2024 09:26
 Subject: Re: Why PG averages are useless
 Viewed: 44 times
 Topic: Price Guide
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zorbanj (872)

Location:  USA, New Jersey
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In Price Guide, peregrinator writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

One easy way of mitigating this issue would be to remove both the highest and
lowest prices before calculating the average.

Or use the median, which this add-on does along with a bunch o other useful features:

https://chromewebstore.google.com/detail/bricktinker/pikfjcohcfpohlckdhdggpcpfdkekomf?hl=en
 Author: Braydensbricks View Messages Posted By Braydensbricks
 Posted: Aug 12, 2024 09:38
 Subject: Re: Why PG averages are useless
 Viewed: 39 times
 Topic: Price Guide
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Braydensbricks (18)

Location:  USA, Texas
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Store: Brayden's Bricks
In Price Guide, zorbanj writes:
  In Price Guide, peregrinator writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

One easy way of mitigating this issue would be to remove both the highest and
lowest prices before calculating the average.

Or use the median, which this add-on does along with a bunch o other useful features:

https://chromewebstore.google.com/detail/bricktinker/pikfjcohcfpohlckdhdggpcpfdkekomf?hl=en

I will definitely be using this, thank you!
 Author: yorbrick View Messages Posted By yorbrick
 Posted: Aug 12, 2024 10:27
 Subject: Re: Why PG averages are useless
 Viewed: 53 times
 Topic: Price Guide
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yorbrick (1193)

Location:  United Kingdom, England
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In Price Guide, peregrinator writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

One easy way of mitigating this issue would be to remove both the highest and
lowest prices before calculating the average.

A seller just has to list two lots (or more) if they want to skew the average.
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 12, 2024 11:32
 Subject: Re: Why PG averages are useless
 Viewed: 25 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
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Store: Cosmic Toys
In Price Guide, yorbrick writes:
  In Price Guide, peregrinator writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

One easy way of mitigating this issue would be to remove both the highest and
lowest prices before calculating the average.

A seller just has to list two lots (or more) if they want to skew the average.

That would be a poor choice, and could suggest that the seller is intentionally
manipulating the averages. Moving towards a quantitative display instead of numerical
averages, would nip that in the bud.

NR
 Author: Ziegelmeister View Messages Posted By Ziegelmeister
 Posted: Aug 12, 2024 11:16
 Subject: Re: Why PG averages are useless
 Viewed: 27 times
 Topic: Price Guide
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Ziegelmeister (300)

Location:  USA, Ohio
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Aug 27, 2021 Contact Member Seller
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In Price Guide, peregrinator writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

Probably means the outliers.
 Author: StarBrick View Messages Posted By StarBrick
 Posted: Aug 12, 2024 12:01
 Subject: Re: Why PG averages are useless
 Viewed: 28 times
 Topic: Price Guide
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StarBrick (7172)

Location:  Netherlands, Gelderland
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Store: StarBrick's BrickShop
In Price Guide, Ziegelmeister writes:
  In Price Guide, peregrinator writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

Many times pointed out in requested changes, never followed through unfortunately
.

I'm not sure what out of boundaries would mean though?

Probably means the outliers.

That one indeed
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 12, 2024 11:20
 Subject: Re: Why PG averages are useless
 Viewed: 32 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
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Store: Cosmic Toys
In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

No, but displaying the data in a better way, means that numbers with no basis
in reality, will (effectively) vanish. Sellers must patrol their own numbers,
and not depend on good Samaritans. Better tools are needed to help all sellers
accomplish this task.

NR
 Author: Ziegelmeister View Messages Posted By Ziegelmeister
 Posted: Aug 12, 2024 11:34
 Subject: Re: Why PG averages are useless
 Viewed: 28 times
 Topic: Price Guide
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Ziegelmeister (300)

Location:  USA, Ohio
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Aug 27, 2021 Contact Member Seller
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Store: Ziegelmarkt
In Price Guide, cosmicray writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

No, but displaying the data in a better way, means that numbers with no basis
in reality, will (effectively) vanish. Sellers must patrol their own numbers,
and not depend on good Samaritans. Better tools are needed to help all sellers
accomplish this task.

Back when I started someone reached out to me when I missed a decimal and priced
something around $8000 instead of $80. Since then I've done the same - especially
when they price something for $0.80 instead of $80. It just takes a minute to
message them.

There are a handful of parts/figs where I want so badly to reach out to sellers
and tell them they can easily charge 25-30% more due to growing scarcity but
that would be price manipulation and borderline collusion.
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 12, 2024 11:48
 Subject: Re: Why PG averages are useless
 Viewed: 26 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
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Store: Cosmic Toys
In Price Guide, Ziegelmeister writes:
  In Price Guide, cosmicray writes:
  In Price Guide, StarBrick writes:
  That works fine, but doesn't eliminate or prevent the errors....

Out-of-boundaries priced items should be removed from this calculation by BL.

No, but displaying the data in a better way, means that numbers with no basis
in reality, will (effectively) vanish. Sellers must patrol their own numbers,
and not depend on good Samaritans. Better tools are needed to help all sellers
accomplish this task.

Back when I started someone reached out to me when I missed a decimal and priced
something around $8000 instead of $80. Since then I've done the same - especially
when they price something for $0.80 instead of $80. It just takes a minute to
message them.

There are a handful of parts/figs where I want so badly to reach out to sellers
and tell them they can easily charge 25-30% more due to growing scarcity but
that would be price manipulation and borderline collusion.

The vast majority of my uploads are done via an XML file. When I submit the XML
for verification, down at the bottom it tells me the dollar total of what I'm
uploading. I guarantee you that if I made the error you describe, I would catch
it right there (and obviously not finish the upload).

NR
 Author: Admin_Russell View Messages Posted By Admin_Russell
 Posted: Aug 12, 2024 09:51
 Subject: Re: Why PG averages are useless
 Viewed: 109 times
 Topic: Price Guide
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Admin_Russell

Location:  USA, California
Member Since Contact Type Status
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BrickLink Administrator
Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR
 Author: zorbanj View Messages Posted By zorbanj
 Posted: Aug 12, 2024 10:20
 Subject: Re: Why PG averages are useless
 Viewed: 66 times
 Topic: Price Guide
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zorbanj (872)

Location:  USA, New Jersey
Member Since Contact Type Status
Dec 14, 2003 Contact Member Seller
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Store: ZorbaNJ's Bricks
On a similar vein (from a reddit discussion):

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6020#T=P&C=88

Last 6 Months Sales:

Max Price US $3,072.37



In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR
 Author: Braydensbricks View Messages Posted By Braydensbricks
 Posted: Aug 12, 2024 11:28
 Subject: Re: Why PG averages are useless
 Viewed: 41 times
 Topic: Price Guide
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Braydensbricks (18)

Location:  USA, Texas
Member Since Contact Type Status
Jul 12, 2021 Contact Member Seller
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Store: Brayden's Bricks
In Price Guide, zorbanj writes:
  On a similar vein (from a reddit discussion):

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6020#T=P&C=88

Last 6 Months Sales:

Max Price US $3,072.37



In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

I was the one that posted about this one... I don't understand how that
could happen lol
  
  
  
Note that the grouping is neither the Average nor the Quantity Average.

NR
 Author: Admin_Russell View Messages Posted By Admin_Russell
 Posted: Aug 12, 2024 13:18
 Subject: Re: Why PG averages are useless
 Viewed: 83 times
 Topic: Price Guide
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Admin_Russell

Location:  USA, California
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May 9, 2017 Contact Member Admin
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BrickLink Administrator
In Price Guide, Braydensbricks writes:
  In Price Guide, zorbanj writes:
  On a similar vein (from a reddit discussion):

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6020#T=P&C=88

Last 6 Months Sales:

Max Price US $3,072.37



In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

I was the one that posted about this one... I don't understand how that
could happen lol

It has been taken care of. Please report things like this to us when you see
them. As you can imagine, it was not a real order.
 Author: ScubaSteve View Messages Posted By ScubaSteve
 Posted: Aug 12, 2024 13:41
 Subject: Re: Why PG averages are useless
 Viewed: 52 times
 Topic: Price Guide
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ScubaSteve (49)

Location:  Canada, Alberta
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Store: Scuba Steve
In Price Guide, Admin_Russell writes:
  In Price Guide, Braydensbricks writes:
  In Price Guide, zorbanj writes:
  On a similar vein (from a reddit discussion):

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6020#T=P&C=88

Last 6 Months Sales:

Max Price US $3,072.37



In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

Also review 21325. A set listed @ $33,297.98 when an average price should around
early/mid $300.00. Thanks
  
  
  
  

In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

I was the one that posted about this one... I don't understand how that
could happen lol

It has been taken care of. Please report things like this to us when you see
them. As you can imagine, it was not a real order.
 Author: Admin_Russell View Messages Posted By Admin_Russell
 Posted: Aug 12, 2024 13:48
 Subject: Re: Why PG averages are useless
 Viewed: 96 times
 Topic: Price Guide
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Admin_Russell

Location:  USA, California
Member Since Contact Type Status
May 9, 2017 Contact Member Admin
Buying Privileges - OKSelling Privileges - OK
BrickLink Administrator
In Price Guide, ScubaSteve writes:
  In Price Guide, Admin_Russell writes:
  In Price Guide, Braydensbricks writes:
  In Price Guide, zorbanj writes:
  On a similar vein (from a reddit discussion):

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6020#T=P&C=88

Last 6 Months Sales:

Max Price US $3,072.37



In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

Also review 21325. A set listed @ $33,297.98 when an average price should around
early/mid $300.00. Thanks

Thank you. Average price is now $237.45 USD
 Author: Braydensbricks View Messages Posted By Braydensbricks
 Posted: Aug 12, 2024 14:11
 Subject: Re: Why PG averages are useless
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Braydensbricks (18)

Location:  USA, Texas
Member Since Contact Type Status
Jul 12, 2021 Contact Member Seller
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Store: Brayden's Bricks
In Price Guide, Admin_Russell writes:
  In Price Guide, Braydensbricks writes:
  In Price Guide, zorbanj writes:
  On a similar vein (from a reddit discussion):

https://www.bricklink.com/v2/catalog/catalogitem.page?P=6020#T=P&C=88

Last 6 Months Sales:

Max Price US $3,072.37



In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

I was the one that posted about this one... I don't understand how that
could happen lol

It has been taken care of. Please report things like this to us when you see
them. As you can imagine, it was not a real order.

I figured, thank you and I will report these from now on!
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 12, 2024 11:28
 Subject: Re: Why PG averages are useless
 Viewed: 53 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
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Store: Cosmic Toys
In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

https://www.bricklink.com/v2/catalog/catalogitem.page?P=32534&idColor=77#T=P&C=77

I wasn't trying to point a finger at one seller, I was trying to illustrate
why simple averages can be easily broken by one poor data entry. A very long
time ago, I read a book that has much to do with why I believe in visual displays
over numerical averages.

NR
 Author: StarBrick View Messages Posted By StarBrick
 Posted: Aug 12, 2024 12:05
 Subject: Re: Why PG averages are useless
 Viewed: 53 times
 Topic: Price Guide
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StarBrick (7172)

Location:  Netherlands, Gelderland
Member Since Contact Type Status
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Store: StarBrick's BrickShop
Indeed, it's not the symptom that needs fixed, the cause needs to be fixed.
Like the Chrome extension provides: usage of the mean values instead of average
might be a BIG improvement and probably not too difficult to create ?
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 12, 2024 13:28
 Subject: Re: Why PG averages are useless
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 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
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Store: Cosmic Toys
In Price Guide, StarBrick writes:
  Indeed, it's not the symptom that needs fixed, the cause needs to be fixed.
Like the Chrome extension provides: usage of the mean values instead of average
might be a BIG improvement and probably not too difficult to create ?

I would happily settle for a way to export (in XML or similar) the values I see
when I'm looking at a PG long form page. That would give me the ability to
do a chart process on it.

NR
 Author: StarBrick View Messages Posted By StarBrick
 Posted: Aug 13, 2024 07:22
 Subject: Re: Why PG averages are useless
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 Topic: Price Guide
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StarBrick (7172)

Location:  Netherlands, Gelderland
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Store: StarBrick's BrickShop
That still doesn't FIX the issue but BYPASSES it.
Say you are uploading 1000 different items from BrickStore.
Then you need to do 1000 times the operation you describe.

When adding 1 set to your inventory, it will work, but for mass-uploading items,
it is a NO GO....

@BrickLink: please fix this.
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 14, 2024 17:12
 Subject: Re: Why PG averages are useless
 Viewed: 41 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
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Store: Cosmic Toys
In Price Guide, StarBrick writes:
  That still doesn't FIX the issue but BYPASSES it.
Say you are uploading 1000 different items from BrickStore.
Then you need to do 1000 times the operation you describe.

When adding 1 set to your inventory, it will work, but for mass-uploading items,
it is a NO GO....

@BrickLink: please fix this.

At the end of the day, I'm not convinced it's a BL issue (at where/why
it's happening). If my theory is correct, that the sellers are entering as
cents, and not fractional dollars, then it may be one 3rd party app that isn't
giving proper feedback as to how the number being typed is going to be handled.
A smart application will take it, clean it up (as much as is possible), then
display it in a common format that makes it explicitly clear how it will be handled.

NR
 Author: SezaR View Messages Posted By SezaR
 Posted: Aug 13, 2024 17:56
 Subject: Re: Why PG averages are useless --> trimmed mean
 Viewed: 53 times
 Topic: Price Guide
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SezaR (1450)

Location:  Canada, British Columbia
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Store: Sezar's trains
In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR

Some listings always appear to have strange outliers.

I suggest to add

"trimmed mean", i.e. "Truncated mean"

This means the mean is calculated based on the 80% of the values (prices) that
are in the middle, and so the top 10% and bottom 10% outliers are ignored. This
gives a more accurate
and stable mean and people pricing their items using truncated mean can be ascertain
their pricing is close to the real average.
 Author: yorbrick View Messages Posted By yorbrick
 Posted: Aug 14, 2024 02:14
 Subject: Re: Why PG averages are useless --> trimmed mean
 Viewed: 35 times
 Topic: Price Guide
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yorbrick (1193)

Location:  United Kingdom, England
Member Since Contact Type Status
Apr 11, 2011 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
Store Closed Store: Yorbricks
  I suggest to add

"trimmed mean", i.e. "Truncated mean"

This means the mean is calculated based on the 80% of the values (prices) that
are in the middle, and so the top 10% and bottom 10% outliers are ignored. This
gives a more accurate
and stable mean and people pricing their items using truncated mean can be ascertain
their pricing is close to the real average.

This isn't more accurate, it is less accurate as it ignores 20% of the data
after sorting it. If doing that, then why not ignore 100% minus one data point
which is equivalent to using the median instead of the mean.
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Aug 14, 2024 12:01
 Subject: Re: Why PG averages are useless --> trimmed mean
 Viewed: 30 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
Oct 1, 2000 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
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Store: Cosmic Toys
In Price Guide, SezaR writes:
  In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR

Some listings always appear to have strange outliers.

I suggest to add

"trimmed mean", i.e. "Truncated mean"

This means the mean is calculated based on the 80% of the values (prices) that
are in the middle, and so the top 10% and bottom 10% outliers are ignored. This
gives a more accurate
and stable mean and people pricing their items using truncated mean can be ascertain
their pricing is close to the real average.

I prefer a visual representation of the grouping, where I can see both the price
spread and the quantity offered spread.

NR
 Author: SezaR View Messages Posted By SezaR
 Posted: Aug 14, 2024 16:16
 Subject: Re: Why PG averages are useless --> trimmed mean
 Viewed: 34 times
 Topic: Price Guide
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SezaR (1450)

Location:  Canada, British Columbia
Member Since Contact Type Status
Jan 15, 2015 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
Store: Sezar's trains
In Price Guide, cosmicray writes:
  In Price Guide, SezaR writes:
  In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?


In Price Guide, cosmicray writes:
  One seller forgets to enter a decimal place, and it throws the average completely
out of whack. The chart, which I generated manually via a spreadsheet, is much
more representative of the data, and shows you immediately where the grouping
is. By manipulating the X-axis, I blew the errant entry off the right side.

Note that the grouping is neither the Average nor the Quantity Average.

NR

Some listings always appear to have strange outliers.

I suggest to add

"trimmed mean", i.e. "Truncated mean"

This means the mean is calculated based on the 80% of the values (prices) that
are in the middle, and so the top 10% and bottom 10% outliers are ignored. This
gives a more accurate
and stable mean and people pricing their items using truncated mean can be ascertain
their pricing is close to the real average.

I prefer a visual representation of the grouping, where I can see both the price
spread and the quantity offered spread.

NR

That's nice but my suggestion should easily be implemented by the software
team.
Also, people can easily set price based on mean, trimmed mean,... on a huge lot
of parts using brickstore with no need to check any visual representation.
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Sep 14, 2024 10:41
 Subject: Re: Why PG averages are useless
 Viewed: 37 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
Oct 1, 2000 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
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Store: Cosmic Toys
In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

Where/How is the place designated to report prices that are wildly out of line
?

I'm trying to do that right now, but none of the choices under "Problem
Item For Sale Report" seem appropriate. Help me to do this correctly.

NR
 Author: 1001bricks View Messages Posted By 1001bricks
 Posted: Sep 14, 2024 10:43
 Subject: Re: Why PG averages are useless
 Viewed: 35 times
 Topic: Price Guide
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1001bricks (53177)

Location:  France, Provence-Alpes-Côte d'Azur
Member Since Contact Type Status
Sep 6, 2005 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
Store: 1001bricks
In Price Guide, cosmicray writes:
  In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

Where/How is the place designated to report prices that are wildly out of line
?

I'm trying to do that right now, but none of the choices under "Problem
Item For Sale Report" seem appropriate. Help me to do this correctly.

?
 
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Sep 14, 2024 12:50
 Subject: Re: Why PG averages are useless
 Viewed: 22 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
Oct 1, 2000 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
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Store: Cosmic Toys
In Price Guide, 1001bricks writes:
  In Price Guide, cosmicray writes:
  In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

Where/How is the place designated to report prices that are wildly out of line
?

I'm trying to do that right now, but none of the choices under "Problem
Item For Sale Report" seem appropriate. Help me to do this correctly.

?

I guess in one sense, it might be thought of as frivolous. That was not my first
interpretation, but I'll go with that one and see what comes of it.

thanks !

NR
 Author: SylvainLS View Messages Posted By SylvainLS
 Posted: Sep 14, 2024 13:18
 Subject: Re: Why PG averages are useless
 Viewed: 31 times
 Topic: Price Guide
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SylvainLS (46)

Location:  France, Nouvelle-Aquitaine
Member Since Contact Type Status
Apr 25, 2014 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
Store Closed Store: BuyerOnly
BrickLink Discussions Moderator (?)
In Price Guide, cosmicray writes:
  […]
I guess in one sense, it might be thought of as frivolous. That was not my first
interpretation, but I'll go with that one and see what comes of it.

You can get there from the store: click on the image of the lot, and, at the
top of the dialog, there’s a direct link to the form, with the lot ID already
filled.

And, of course, you can go to the lot in the store from the Price Guide.

So:
— see the offending lot in the PG,
— click on the flag,
— click on the image,
— click on the link,
— fill in the form,
— click on Submit Complaint.

Click click click… but no ID to memorize, and seeing the lot in the store allows
to see if there’s any note explaining the price
 Author: cosmicray View Messages Posted By cosmicray
 Posted: Sep 14, 2024 10:48
 Subject: Re: Why PG averages are useless
 Viewed: 39 times
 Topic: Price Guide
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cosmicray (3529)

Location:  USA, Florida
Member Since Contact Type Status Collage
Oct 1, 2000 Contact Member Seller
Buying Privileges - OKSelling Privileges - OK
View Collage Pic
Store: Cosmic Toys
In Price Guide, cosmicray writes:
  In Price Guide, Admin_Russell writes:
  Please report things like this. What is the part number?

Where/How is the place designated to report prices that are wildly out of line
?

I'm trying to do that right now, but none of the choices under "Problem
Item For Sale Report" seem appropriate. Help me to do this correctly.

NR

To piggyback on this subject, and to put a slight twist on it, currently there
are no instances of this item listed in North America as NEW, nor have their
been any sales in North American as NEW. So the two I have to list are coming
in with no comps to establish a valid price range for NEW. My anticipated price
is certainly less than one USED lot, which is wildly overpriced (roughly x100).
So here we are.

NR