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Best way to calculate the "correct" price
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Kallahar
The Scope
Gallente Federation
#1 - 2011-10-12 16:51:22 UTC
I run http://eve-marketdata.com which is a market info site. One of the primary features is to show the "correct" price of an item. So, for example, if you're off in the hinterlands of 0.0 and want to know "is 2,000,000isk a good price for a 1mn microwarpdrive ii"? You can open the site, type it in, and find out "oh, that's a 30% markup, good enough!"

Currently to calculate the "jita price" I do a simulated buy of 5% of the items for sale and take the average price. That way it removes the scams and the ones that are ridiculously priced. However, items that don't sell very often, like a Dark Blood Xray M, are hard to calculate.

The other option is to use the "history" data which has the average price for that day. But, while people upload jita price data on average twice a day, history data is often a week or more old...

So, what method do you guys think is more accurate?

Thanks!

Kallahar
Scrapyard Bob
EVE University
Ivy League
#2 - 2011-10-12 20:15:54 UTC
I don't know that there is a better way - other then collecting data across multiple regions and throwing out the outliers.

The 5% buy sim price is pretty hard to game on anything that trades in decent volumes. But I still tend to pull multiple regions and compare the buy-sim prices across those regions just in case someone has gone insane in one of the trade hubs and is trying for a monopoly.
Callean Drevus
Perkone
Caldari State
#3 - 2011-10-12 20:51:39 UTC
Even a 5% simulated buy (while by a large margin the best method) is not perfect. It tends to do some weird things in mostly Jita, where people post orders for gazillions of items at a price of 0.01 isk (PLEX is a good example). This leads to the top 5% comprising the entire (valid) market and a few millions or so of the outliers reducing the average to pretty much bullshit.

You could use the historical price to determine whether something is idiotic (any price under 1 isk is idiotic and should be filtered by default)..

Developer/Creator of EVE Marketeer
Scrapyard Bob
EVE University
Ivy League
#4 - 2011-10-13 14:38:44 UTC  |  Edited by: Scrapyard Bob
One option might be to calculate both a buy-sim / sell-sim price based on 5% of the unit volume, and a second buy/sell sim price based on the ISK volume of the orders.

The ISK volume method might work better for calculating buy-orders, the unit volume probably tends to work better for sell-orders.

(Some of the PI products regularly trade below 1 ISK, Noble Gas is about 0.93 ISK/unit.)
Dane El
Negative Density
#5 - 2011-10-13 14:44:16 UTC
Who cares about the "correct" price? If I can sell it for an acceptable margin above what I bought it for, I'm selling.
If I have any doubts about a price I'm seeing being out of line, the in-game market history is sufficient to identify prices you can't count on lasting.

I really don't see the need to make trade analysis more complicated.

1. Buy items cheaply.
2. Account for taxes and fees.
3. Sell for more than procurement cost.

Repeat until you're satisfied with your wallet balance.
Callean Drevus
Perkone
Caldari State
#6 - 2011-10-13 17:20:48 UTC
Scrapyard Bob wrote:
(Some of the PI products regularly trade below 1 ISK, Noble Gas is about 0.93 ISK/unit.)


Hmmz, will have to make an exception there then. Trit used to represent the absolute minimum for me ;)

Developer/Creator of EVE Marketeer
Kallahar
The Scope
Gallente Federation
#7 - 2011-10-14 17:05:59 UTC
Excellent replies, thanks everyone! I think I'm going to add a second layer of checks. If the number of orders is low, or if the calculated daily rate is off by too much from the historical average, then use the historical average instead. That should give the most accurate number for both high-volume items and the rarely sold supercap BPO.

Kallahar
SencneS
Viziam
Amarr Empire
#8 - 2011-10-16 20:08:11 UTC
There is no "more accurate" way to calculate price than 0.01 ISK below the lowest seller with the stipulation it will generate at least 0.01 ISK more then what you acquired it for.

There is no real reason to look at an external price source. You could argue if you find a mod which doesn't have any on the market (low/null sec) but is in my opinion a "push" argument. On one hand you have zero competition, on the other, you don't want to price it so high that it makes it worth while to travel 20 jumps to buy it.

Some of the best selling items in nullsec are the simple cheap stuff with 200% markups. Why limit yourself to 30% in a region you have zero competition...
Diomedes Calypso
Aetolian Armada
#9 - 2011-10-16 21:22:05 UTC
From experience I can assure you that you can add 500k to a 1 million isk item and sell it at a routine pace from a system 3 jumps away.

... best way to do that is to be in a region other than The Forge or Domain...

Stock a station no one else is trading in with 50 to 100 to 200 t2 or named items (more is better). If you're doing lower numbers try to focus on having enough to outfit a couple different types of ships more completely.,.. drake being high on your list.

Life will be much easier if someone in the system or surrounding is manufacturing and selling ships.. esle you got to bring those in . which means freighters or mutiple trips and actually both.. and they are really a loss leader as you'll be lucky to get more than a few million more than the hubs for the ship...

... the ships are a loss leader.

But,,, yeah, I'll sell invulnerablity fields for 1.7 million when they're 1.1 , 3 or 4 jumps away.

.
Companion Qube
Pator Tech School
Minmatar Republic
#10 - 2011-10-17 08:54:55 UTC  |  Edited by: Companion Qube
Keep in mind that everything in this game is an estimate, by the time you move product to market prices have usually changed. If you want to make people happy I'd provide them with a few options to choose from:

Lowest sell
Highest buy
simulated lowest sell average (your 5% method)
simulated highest buy average (5% average of the high buys)

and my favorite for quick estimations: (highest buy + lowest sell) / 2 - aka, the spread midpoint.

People prefer different ways of estimating profit - let them pick.

edit: back when I actually cared about estimating prices with spreadsheets I used excel's HARMEAN function a lot, taking the harmonic mean of a market export then filtering everything more than 3 sigma away from that point tended to weed out the crap orders pretty effectively.
Scrapyard Bob
EVE University
Ivy League
#11 - 2011-10-20 04:47:38 UTC
One thing that I'd like to see is a rolled up price that does the 5% buy sim over multiple hi-sec trade hubs (Jita, Amarr, Dodixie, Rens and maybe as many as 8-10 in total). That would make tools like jEVEAssets able to pull a single price that is much more representative of the approximate value of assets rather then it bouncing up and down rapidly as people try to pull various market manipulations in Jita.

While Jita may be the most competitive, it's also the easiest price index to "game" on a lot of products. There will be days when the Jita price for item XYZ suddenly goes from 100k per unit to 5M ISK/u just because someone is trying to corner the market. Which screws up lots of graphs and makes it harder to spot overall trends. A weighted average of the other regional trade hubs would lessen that effect.
Scrapyard Bob
EVE University
Ivy League
#12 - 2011-10-20 04:58:08 UTC
Right now, I can think of a few ways to game prices:

Sell Orders:

1) Put up a few units of something for an absurdly high price (such as the 8,888,888 ISK shuttles). Usually the 5% buy-sim for the entire region tends to kick those out. A weighted average might work, but you might also need to drop data points that are too far out of sync with the rest of the market. (Harm mean? Standard deviation?)

Buy orders:

1) Buy orders of 0.01 ISK are common and really don't affect things too much as long as the average is a weighted average. It just means that there isn't anyone willing to plunk down real ISK for that item via a buy order.

2) Buy orders where the price is high and the minimum quantity is equal to (or nearly) the entire order quantity are a common scam where the buyer puts up a buy order that simply cannot complete (due to the wallet not having enough ISK). For the "sell-sim" price, it can get fooled by these. So you might have to drop out any buy orders where the minimum qty is > 50% of the total quantity before calcuating any averages / means / sell-sim price.