Costs and benefits of items in invention

The recent poor run of inventions made me think about how to improve this aspect so that I get a more reliable "flow" of tech II BPCs to build from. I haven't so far been using any "base items" in my invention so I thought I would work out the effect they would have. Base items are simply the meta 1/2/3/4 version of the item you are trying to invent, and they get consumed in the invention job.

The table below shows the chances of success with and without items. I've also calculated the averge cost of one success based on a theoretical 1 million isk cost of the datacores required. This means I can also calculate the actual benefit (in terms of isk) of the item.

	Chance	Average cost per success	Average benefit of item
No item	50.4%	1,984,127
Meta 1	52.5%	1,904,762	79,365
Meta 2	56.0%	1,785,714	198,413
Meta 3	63.0%	1,587,302	396,825
Meta 4	84.0%	1,190,476	793,651

The average cost of datacores for me is not exactly 1 million but varies per job and varies over time depending what the datacores cost, so here are the equations to use to calculate your own table:

• The chance of success I have taken from this very useful website and the chances shown in the table above are for max skills (5/5/5 in the appropriate 2 science skills and the racial encryption skill)
• Average cost of success = (1/chance) x cost of datacores
• Average benefit of item is just a simple subtraction of the meta item you want to calculate less the cost per success with no item

So, using this information, I can set up some "buy" orders in mission hubs and hopefully snap up some items to use. I'm not optimistic about getting many meta 4 items at a good price - they tend to go for millions compared to a benefit of under a million isk. But the meta 1/2/3 for many items I should be able to get hold of.

As long as I pay less than the "average benefit of item" (using the actual value of my own datacores, not the illustrative 1m isk cost of datacores used in the table above, obviously) then this not only helps my profit margins but also should help me get a more reliable flow of inventions. Win/win!