 # Making sense of Industry Install Costs

Hi all. I’m looking for some assistance on how the job cost is calculated since the numbers that Eve produces don’t make sense with the numbers Eve is giving me.

As an example I’m setting up to build one Atron. These numbers are pulled from EVE itself. The problem is this doesn’t make sense with my calculations

215055.48 * 2.28 = 4903.26 (rounded) not 4906

and furthermore

4906 - 196 = 4710 not 4711

So what’s going on here? Does eve do some sort of weird rounding up somewhere?

Most likely all of the confusion descends from it using a higher precision value for the system cost index calculation but rounding the displayed value for aesthetics/ease of use.

Find out what the actual system cost index is and start with that.

4,906 is 2.28% of 215,055

-4% of 4,906 is 196

236 is +5% of 4,711

4,711 + 236 is 4,947

No, it isn’t.

4903.254 is 2.28% of 215,055.

Which was basically the whole point of the question your explanation doesn’t answer.

He knows what the steps are, he didn’t understand why the arithmetic appears to be incorrect, which it does, because the displayed precision differs from the precision used in the calculations.

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Just from checking the industry window approximately every 30 minutes I’ve noticed the arithmetic keeps fluctuating but the base numbers show the same as before. According to this picture the system index should be 2.278017% ( 4899 / 215055.48 )

At least the subtraction was correct this time around.

I even tried pulling up the numbers with the API into google docs but the most precise number for system index I can get matches what’s shown in game, 2.28%.

It’s not the end of the world as far as my calculcations go. A few errant ISK here isn’t going to make or break my profit predictions. I was just curious if there was a secret way to get that exact system index number that seems to be the key to making this calculation work.

The actual SCI formula is Sqrt(SystemJobHours/GlobalJobHours) for the last 28 days, so the odds of it ever being actually 2.28 are basically nil. It’s pretty much always something like, well… 2.278017, for instance.

AFAIK, though, no, there isn’t a display of the “real” value (and it does update quite frequently, as you’ve noticed).

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The precise number isn’t shown, as it was, at one time, possible to work how how many job hours were put in over all of new eden, and when, with fair accuracy.

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