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How to determine #of items Sold over a timeframe? Demand?
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Zifrian
The Frog Pond
Ribbit.
#1 - 2012-01-21 03:06:40 UTC
I'm working with EVE Central data and have looked at others but I can't seem to come up with a way to use the data there to determine how many of a particular item have sold over a time period. I have a feeling that this won't be possible unless I built my own program like EVE Central and store massive amounts of historical data, but I could also be overlooking something as several websites for industry/trade advertise ways to determine the demand of certain items. I'm not sure how they do it if they are really giving accurate data.

What I'm looking for is, I want to sell item X, if I knew how many of item X were sold in say Jita each day for the past 5 days, I could take the amount and then analyze it with my production time of X or other factors to measure demand and decide if it's worth the time to build. I don't think this functionality exists. There is a volume number in the EVE Central upload, but that's not really what I'm looking for. The number of items for sale (volume) on any day doesn't measure demand (which would require # of items sold). In the API there is no "Moved" value that I can see but it does show up on the website. That seems to be what I'm looking for but I'm at a loss of how to get it.

Again, if I used the market log data, I could compare order numbers to previous ones and then calculate from the start volume to the current volume, the number of items sold. But it doesn't look like I can get that from EVE Central or any other website.

Am I off here? Something I'm missing? Any help would be great.

Thanks

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Callean Drevus
Perkone
Caldari State
#2 - 2012-01-21 10:27:43 UTC
You are missing something :) EVE Marketeer has long been gathering history data, and has functionality that allows you to take an average of the items moved in the last x days. The feature that allows you to actually retrieve this data is relatively new though: http://www.evemarketeer.com/api/averages/10000002/30/34/xml

Oh, it only allows you to get this data by region though, since there is no actual data per station/solar system.

Originally I also tracked the changes between individual orders, but that proved to just provide way too much inaccurate data, that was very little used. There is a possibility I'll add this again (or rather, there's a certainty I'll do that), but it won't happen in the foreseeable future.

Developer/Creator of EVE Marketeer
Zifrian
The Frog Pond
Ribbit.
#3 - 2012-01-21 11:17:44 UTC  |  Edited by: Zifrian
OK yeah, I was looking at your site and trying to figure out how to use it so this is helpful. However, when I enter anything other than 30 I don't get a result. However, this may not be a big issue.

Looking at this: http://www.evemarketeer.com/api/averages/10000002/30/640/xml

Is the average, the daily average movement and min/max daily as well? Also, is this sell data only or buy and sell data? Reason I ask is I'm not sure buy data is all that useful for looking at demand.

What are the est_bpct and est_spct flags for?

Thanks for the help!

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Callean Drevus
Perkone
Caldari State
#4 - 2012-01-21 13:02:35 UTC
I suggest you look at http://www.evemarketeer.com/api

And open the 'Historical Averages' tab, for more information and a description of all the fields.

The average given is for all transactions, but using est_bpct I try to make an estimate of how much of those are actually buy, or actually sell orders. The average and min max are daily averages.

Developer/Creator of EVE Marketeer
Zifrian
The Frog Pond
Ribbit.
#5 - 2012-01-21 16:01:07 UTC
Ahh missed the bottom tabs. Thanks

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