A question about GNP

[Byrath]

Under the Demographics tab, there is a line graph for 'GNP' and it is also listed on the chart that shows how you stack up against 'rival best', 'rival average', etc.
I understand that it is an economic reading of some kind, and that it stands for Gross National Product, but I'd like some insight as to what it actually measures in game.
My line on the graph has been bouncing up and down like crazy for the past 100 turns or so, and is actually lower now than it was before I started placing universities, banks and observatories in my commerce cities. Meanwhile, the three competitive AI civs GNPs have been climbing fast during that time period .. I had a nearly 2-1 lead on the top AI 100 turns ago and now I am in second place
I tried to attach a save if anyone cares to comment on my situation (I'm running SevoMod on Vanilla Civ), but mainly looking for answers about GNP. Thanks.

 

[namliaM]

There is a demographics explained thread somewhere (I am to lazy to go and find if for you)

GNP = Gross commerce - cost

Your GNP then gets altered by banks/libs/markets/uni's etc.

So in actuallity your GNP doesnt really say much, you can have the best GNP and the lowest Beaker+Gold count in the game.

 

[Byrath]

Ahh, thanks for the info. That helps explain the wild fluctuations in my GNP (changing civics adjusting my costs, and later adjusting my base commerce when switching to Universal Suffrage or whichever it is that gives +2 per town). It also explains why I appear to be still out-teching the AI's despite my GNP taking a dive, as I have Academy in 4 cities. 100% modifier in one city, 10% from Free Speech, and Uni's/Observatories that they do not.

 

[nullspace]

This strategy article The inner workings of the Demo screen explained has more details. Apparently the GNP calculation changed in BtS to be more useful and accurate.

 

[lauralaura]

This really is a highly misleading number. It's not uncommon for me in the later game to be teching nicely at 60-70%, pulling in 200gpt, while my GNP figure is actually negative.

 

[magicalsushi]

I don't think I've ever had a negative GNP in Civ 4; I didn't realise it was possible. Well, maybe if you over-expand, I guess, but I always play very conservatively so my games never get that interesting. My GNP was routinely negative in Civ 2 no matter how well I was doing; I've actually found the GNP figure in Civ 4 to be quite useful. Perhaps I'm putting too much faith in its accuracy though.

Does it include the effect of research-boosting buildings like libraries in BtS, or are those not counted?

 

[CivDude86]

Shrines and merchants weren't counted (should be in BtS) so its easy to get a negative GNP if you make a good bit of that doesn't come from . I usually fill my holy city up with great prophets and merchants so thats 100-200 not being counted.