AI - human trade revealed

[Nor Me]

I did another test. I created two scenario which differed only by a modded civ. In one, the Iroqouis had the least agression level, were European and favoured Republic. In the other, they had the highest agression level were American and shunned Republic. I was a French republic.

When everything was in my favour I got AI-human bonuses of:
Chieftain 100.0%
Regent: 100.0%
Deity: 105.0%

When evreything was against me:
Chieftain: 100.0%
Regent: 109.0%
Deity: 122.0%

Yes, they are all exact percentages. I haven't tested these factors individually yet.

[vmxa1]

The question I have is that the developers have said all along that the game does not know the AI from the Human. If that is so how can it treat one party differently? Could not these discrepancies be accounted for by other factors.

[wilbill]

theNiceOne, Thanks for this very helpful information.

[Catt]

Originally posted by Nor Me
[. . .]

When everything was in my favour I got AI-human bonuses of:
Chieftain 100.0%
Regent: 100.0%
Deity: 105.0%

When evreything was against me:
Chieftain: 100.0%
Regent: 109.0%
Deity: 122.0%

[. . .]

Curiouser and curiouser. Good work NorMe and theNiceOne!

Catt

[Theseus]

Well done, indeed.

I always wondered why tech leads seemed SO much more important / rewarding on higher levels.

It bugs me a little that this was never reported by Firaxis, especially at Regent, but I also think it's very, very elegant. I've never liked the *outnumbering* approach to the AI higher levels, but like the stuff that just makes the game harder. Kudos, Firaxis.

[theNiceOne]

RonO: I didn't check this. Both the AI and the human were in despotism when the tests were done.

I didn't really try to check everything that affects tech trade cost, only how difficulty levels affect it.

So there are more testing that can be done here.

The base trade cost (ignoring number of civs that have the tech and number of civs total) of a tech is probably (my guess) computed something like this:

[(Research cost * A + B) / CF + C] * AH + D

CF = Cost factor: 1 on regent an below, 0.9 on monarch, 0.8 on emperor and 0.6 on deity.
AH = AI-human bonus as described in the first post.

Where factors that don't affect reserach cost, but affect trade cost (like possible wonders, new resources, attitude etc)are either of type A, B, C or D:

Type A: Factors that are multiplied to the research cost. An annoyed seller could have a factor of type A = 1.1

Type B: Factors that are added to the research cost, and affected by cost factor.

If government availability is a cost factor, then it must be of type A or B, since the cost of republic was directly propotional to CF and AH when no other factors applied.

Type C: Factors that are not affcted by cost factor, but are added before the AH multiplier is applied and thus affected by this. As described in my first post, wonder availability is of this type.

Type D: Factors that are added after all multipliers, and therefore constant regardless of research cost and difficulty level. I would guess that there aren't any such factors, but I don't know.

This got a bit technical, but my point is that there are still a lot of researching to do before we can predict what an AI civ will pay for a tech. I didn't mean to find out everything, only that it is a (until-now) hidden difficulty-dependant modifier that affects the price.

[theNiceOne]

Originally posted by Nor Me
When everything was in my favour I got AI-human bonuses of:
Chieftain 100.0%
Regent: 100.0%
Deity: 105.0%

When evreything was against me:
Chieftain: 100.0%
Regent: 109.0%
Deity: 122.0%

Yes, they are all exact percentages. I haven't tested these factors individually yet.

Good job, Nor Me. I've done some testing as well, and found that values may differ from my initial numbers. It looks like this modifier may itself be modified

I will look more into it when I get the time.