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skovl
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Valueguide request
I use the valueguide very much. It is a good guideline for me when I buy stuff.
What I miss is a "latest 5 auctions" or " latest 10 auctions" line though.
It is well known that an item goes very high when it's new, but often prices drop later on.
The first auctions reported still have influence on the average price after some time.
But if we could get an average price of the latest 5 or 10 auctions it would tell more about the actual price at the moment.
Is it possible to make such a thing???
[Edited on 14-9-2006 by skovl]
[Edited on 14-9-2006 by skovl]
Searching for...
PERSONAL JESUS CD - CENCORED SLEEVE
STRANGELOVE PRO-CD-3213 WITH STICKER - FOUND (W/O STICKER THOUGH  )
THE SINGLES 81>85 + 86>98 MUG
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Devid
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I thought about the same. But I think "Standard Deviation" would be more interesting; something like: "50% of ebay auctions of this item was sold
between x and y €".
P.S. at Thomas: don't say "stuff" if you mean nice DM-items
I don't have to collect to enjoy my collection.
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skovl
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| Quote: | Originally posted by Devid
I thought about the same. But I think "Standard Deviation" would be more interesting; something like: "50% of ebay auctions of this item was sold
between x and y €".
P.S. at Thomas: don't say "stuff" if you mean nice DM-items |
I'm sorry. I'm mean "nice DM items"
Searching for...
PERSONAL JESUS CD - CENCORED SLEEVE
STRANGELOVE PRO-CD-3213 WITH STICKER - FOUND (W/O STICKER THOUGH )
THE SINGLES 81>85 + 86>98 MUG
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peterdegn
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You can always recalculate yourself. I've done that several times.
 Collection + MySpace site
Newest album: Tom Waits - Bad As Me + Leonard Cohen - Old Ideas (lp's)
Newest single: Bikstok Røgsystem - Radio (cd-r single)
Newest visual: Melancholia
Listenin' to: new music |
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skovl
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Then a lot of my "impulse buying" will be stopped, Peter.
Searching for...
PERSONAL JESUS CD - CENCORED SLEEVE
STRANGELOVE PRO-CD-3213 WITH STICKER - FOUND (W/O STICKER THOUGH )
THE SINGLES 81>85 + 86>98 MUG
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Devid
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Anyway, highest, lowest and latest are not very representative for an item's price.
Anyone who studied statistics?? (I had this subject only one year, long time ago)
I don't have to collect to enjoy my collection.
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peterdegn
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| Quote: | Originally posted by skovl
Then a lot of my "impulse buying" will be stopped, Peter. |
I don't get that?
Collection + MySpace site
Newest album: Tom Waits - Bad As Me + Leonard Cohen - Old Ideas (lp's)
Newest single: Bikstok Røgsystem - Radio (cd-r single)
Newest visual: Melancholia
Listenin' to: new music
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worm
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| Quote: | Originally posted by Devid
Anyway, highest, lowest and latest are not very representative for an item's price.
Anyone who studied statistics?? (I had this subject only one year, long time ago) |
Exactly like me. Too long time ago.
| Quote: | Originally posted by Devid
I thought about the same. But I think "Standard Deviation" would be more interesting; something like: "50% of ebay auctions of this item was sold
between x and y €". |
I don't have a clue how to calcaluled that. But I still have my old statistic books in a box down in my basement. I will try to find it.....
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worm
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| Quote: | Originally posted by skovl
What I miss is a "latest 5 auctions" or " latest 10 auctions" line though.
......
Is it possible to make such a thing??? |
Yes, it shouldn't be a big problem. Let me give it a try.
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worm
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Here is a good example where the "Latest 5 average" is useful:
PCDBong35
Average (53 auctions) € 59
Average (latest 5) € 15
This is the only VG uploaded, but all will be uploaded tomorrow with the new feature.
I need help with "Standard Deviation". Can anybdy give an example of how to calculate this? Haven't found my old statistic book....
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davesmichele
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N=number of data values used
X=mean/average
x1, x2, x3, etc = value of each data point used
I cannot write the formula here, so I will describe it. Take each x1, x2, etc value and subtract X, then square each of these values. Once you have
each value, add then together. Multiply this total by 1/N. Then take the square root of this value, this is the standard deviation.
Ex. Square root of [1/N [((x1-X)squared) + ((x2-X) squared) + ((x3-X) squared)]]
That looks ridiculous, lol...you can just use excel if you have it 
Looking for: Bong Mags 4, 7, 10, 25-30, 32-35, 37-39, 52  |
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worm
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let's take this as an example:
Suffer Well PCD
With these entries:
7 29-06-2006 eBay # 330000920117 € 30
6 12-06-2006 eBay # 4891588248 € 18
5 04-05-2006 eBay # 4870579985 € 32
4 24-04-2006 eBay # 4865720539 € 37
3 03-04-2006 eBay # 4861770655 € 33
2 26-03-2006 eBay # 4852749433 € 51
1 26-02-2006 eBay # 7590753045 € 85
How should the Standard deviation be calculated here?
An Excel example would be very fine.
I appreciate your help!
[Edited on 13-10-2006 by worm]
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roosegfb
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| Quote: | Originally posted by worm
let's take this as an example:
Suffer Well PCD
With these entries:
7 29-06-2006 eBay # 330000920117 € 30
6 12-06-2006 eBay # 4891588248 € 18
5 04-05-2006 eBay # 4870579985 € 32
4 24-04-2006 eBay # 4865720539 € 37
3 03-04-2006 eBay # 4861770655 € 33
2 26-03-2006 eBay # 4852749433 € 51
1 26-02-2006 eBay # 7590753045 € 85
How should the Standard deviation be calculated here?
An Excel example would be very fine.
I appreciate your help!
[Edited on 13-10-2006 by worm] |
I would throw away 10% of highest and 10% of lowest values and
then easily build the averaged worth. Anyway, i would publish both. This average and total average.
For the example above you would throw away 18 and 85.
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sausage
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Lars,
Do you need working or just Excel function? Excel formula is just as follows
=STDEV(30,18,32,37,33,51,85)
equals 21.78 btw.
Some links...
wikipedia
another standard deviation example
Hope this helps
Simon
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worm
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Thanks I will have a look at it later. I have now tried the idea with removing highest and lowest 10% to calc the average.
The VG for all Suffer Well is uploaded as a test, like:
Suffer Well PCD
Maybe the name should be different, but at this moment I just write the number of auctions used. Like "Average (5 auctions) € 37"
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worm
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btw. the new features are only availble on items with more than 5 auctions as you can't removed the highest and lowest 10% of only 3 items.
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roosegfb
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| Quote: | Originally posted by worm
btw. the new features are only availble on items with more than 5 auctions as you can't removed the highest and lowest 10% of only 3 items.
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I'm no math expert, but i calculate the worth a way like this when we show the value guide.
Anyway, i think it's a wrong way. Also using the standard math scheme is wrong in my opinion.
another suggestion:
/*
30.10.06 - 30 EUR
26.10.06 - 45 EUR
15.10.06 - 40 EUR
08.10.06 - 70 EUR
01.10.06 - 75 EUR
*/
$timefactor = (((30 * 30) + (45 * 26) + (40 * 15) + (70 * 8) + (75 * 1)) / 80);
// ((value * day) + (value * day) + ...) / summary of days
$peakcleaned = (45 + 40 + 70) / 3;
// kicked out the peaks
$totalavg = (30 + 45 + 40 + 70 + 75) / 5;
// standard average of all value
$worth = ($timefactor * 4 + $peakcleaned * 2 + $totalavg) / 7;
echo $worth;
// 45.79 EUR
[Edited on 13-10-2006 by roosegfb]
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worm
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Very interesting idea. There is something to think about.
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Devid
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Nice idea, Steffen. But what happens to a value if there is a rare item sold every now and then, its value will drop as time goes by??
So I think we should do it in a correct statistically way. And standard deviation is quite easy to calculate and to interpretate.
I don't have to collect to enjoy my collection.
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skovl
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| Quote: | Originally posted by peterdegn
| Quote: | Originally posted by skovl
Then a lot of my "impulse buying" will be stopped, Peter. |
I don't get that? |
if I have to calculate myself, then I have the time to think twice before i hit the buttom -> no more impulse buying
Searching for...
PERSONAL JESUS CD - CENCORED SLEEVE
STRANGELOVE PRO-CD-3213 WITH STICKER - FOUND (W/O STICKER THOUGH )
THE SINGLES 81>85 + 86>98 MUG
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roosegfb
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| Quote: | Originally posted by Devid
Nice idea, Steffen. But what happens to a value if there is a rare item sold every now and then, its value will drop as time goes by??
So I think we should do it in a correct statistically way. And standard deviation is quite easy to calculate and to interpretate.
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Yes, thats a problem. But it's quite easy to adjust the weight of the formular.
In my opinion it's more important to know the up-to-date worth and you can't get it without the factor time.
for example:
$worth = ($timefactor * 2 + $peakcleaned * 2 + $totalavg) / 5;
or
$worth = ($timefactor + $standard_diviated) / 2;
or ...
[Edited on 13-10-2006 by roosegfb]
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worm
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| Quote: | Originally posted by roosegfb
another suggestion:
/*
30.10.06 - 30 EUR
26.10.06 - 45 EUR
15.10.06 - 40 EUR
08.10.06 - 70 EUR
01.10.06 - 75 EUR
*/
$timefactor = (((30 * 30) + (45 * 26) + (40 * 15) + (70 * 8) + (75 * 1)) / 80);
// ((value * day) + (value * day) + ...) / summary of days
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How will you calculate an older item in this formular? Like:
20.09.06 - 90 EUR
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roosegfb
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| Quote: | Originally posted by worm
| Quote: | Originally posted by roosegfb
another suggestion:
/*
30.10.06 - 30 EUR
26.10.06 - 45 EUR
15.10.06 - 40 EUR
08.10.06 - 70 EUR
01.10.06 - 75 EUR
*/
$timefactor = (((30 * 30) + (45 * 26) + (40 * 15) + (70 * 8) + (75 * 1)) / 80);
// ((value * day) + (value * day) + ...) / summary of days
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How will you calculate an older item in this formular? Like:
20.09.06 - 90 EUR |
/*
30.10.06 - 30 EUR day 41
26.10.06 - 45 EUR day 37
15.10.06 - 40 EUR day 26
08.10.06 - 70 EUR day 19
01.10.06 - 75 EUR day 11
20.09.06 - 90 EUR day 1
*/
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roosegfb
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if you use php:
$days_between = round((strtotime('2006-10-30') - strtotime('2006-09-20')) / (60*60*24)) + 1;
$days_between = round((strtotime('2006-10-30') - strtotime('2006-10-01')) / (60*60*24)) + 1;
$days_between = round((strtotime('2006-10-30') - strtotime('2006-10-08')) / (60*60*24)) + 1;
...
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roosegfb
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PS for standard deviation you can ask your admin (sorry, forgot his name) for doing this:
# pecl install stats
and adding the following line to the php.ini
extension=stats.so
after it you can use:
$a=array(30,45,40,70,75,90);
$dev=stats_standard_deviation($a);
echo $dev;
for getting a standard deviation value
like here: http://invsee.asu.edu/srinivas/stdev.html
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