How Supply and Demand Lists Are Determined

[solo]

Having Uranium as a secondary wildcard could be pretty handy! That was good fortune that the quotiemts for the precious metals were relatively simple. Makes it easier to accurately pin down the factors for other commodities. Again, the design implements the scarcity of certain resources very well.

Some of these formulae seem quite "creative" or done the way they were just for the fun of it. From the way the game plays and the look of many of these formulae, it would seem that the number of commodities with a chance of making the supply and demand lists for each city is actually quite limited. When lists change in my games, more often then not it is an old friend coming back into the action, rather than a new arrival.

How much variation are you finding between quotients during your tests?

[samson]

Yes, the Silver/Gems/Gold DQ triad is a real boon. I've finally got a scale founded in hard numbers not just relative ratios. By cranking up the population and tech-editing in Economics and Computers, I can measure DQs within +/- 2. This should allow me to complete the other formulas sooner and maybe even get a handle on Dye and Copper demands. At least I should be able to quantify them.

How much variation are you finding between quotients during your tests?

I'm not sure what you mean.

[solo]

Variation between commodities that make it onto S/D lists and those that don't. Do the losers come close, or is it that their quotients are so much lower that they don't have a chance?

[samson]

My tests aren't typical of game conditions at this stage, so I can't answer your question. And I don't calculate the DQs and SQs of commodities not listed. I'm mostly interested in the degree of change required to shift items on the list.

I've just added Supply formulas for Oil and Spice and Demand for Salt. Only one more to go for the Supply side: Wine, but it's giving me a headache.

[samson]

More demand formulas added: Coal, Silk and Oil. And thanks to William Keenan, a new factor to test for: City Improvements, four of which were found to effect the demand for Oil.

[samson]

Latest updates: Wine, supply and demand; City improvements effects added to Salt, Coal, Silver, and Uranium.

Uranium apparently is only a demand wildcard, not a supply one. If anyone has a game save of Uranium being supplied in a city, I'd much appreciate them posting it. I'd love to analyze it.

The location effects listed in the formulas make the most historical sense when considered on the World Map supplied with the game. For instance, Wine supply is highest in the Northern Hemisphere and at maximum distance from the Dateline. This corresponds to Europe on the world map.

At this point Supply formulas are posted for all commodities. There are four demand formulas still unknown: Dye and Copper (both have high Demand quotients of unknown dependency), Spice (demand reduced by Refrigeration, but shows no correlation with other known factors) and Cloth (which is dependent on terrain and # of Techs, but does not conform to known formula templates.) All of these may remain unknown for some time.

[DrFell]

I recall an old strategy of mine involving a republic->trade tech route combined with early celebrated cities up to size 8-12, and internal trade. I remember an especially large number of cities demanding copper and dye under this strategy, especially ones close to the capital, if that's any help.

[solo]

I'll start checking supply formulae using the cities in my test game.

[samson]

Thanks, that'll be great.

Copper and Dye seem to have the same disease. Using MGE, in which they are more persistent than 2.4.2, I tried to measure their Demand Quotients against Uranium. With 100 techs in a size 13 city Uranium's DQ is 10,000, but that wasn't enough to displace Copper and Dye from the top 2 slots. With a Nuclear Plant and SDI added, U's DQ was 40,000 and still couldn't budge Copper and Dye.

All I've been able to determine them is that Copper's DQ is increased by city size in the regular 3/8/13/... series. And that Dye's DQ is reduced by Chemistry and Mass Production (relative to Copper's) by 1/2 each. Copper's DQ is reduced by Computers by 1/4 relative to Dye. But even with both of these in effect and Uranium's 4x modifier, C & D held the top slots.

[solo]

Here is a save having uranium supplied by 11 cities and demanded by mnay more. I think it's from an MGE game.

[Campo]

I am impressed.

samson and solo, both of you have done some amazing analysis on trade issues.

Good work.

[solo]

Samson,

A few questions, just to make sure I'm doing this right:

In several situations, lack of certain terrains produces a zero on one half of an terrain equation, causing a net result of zero, right? (Example, no ocean or rivers mean no spice)

Am I right in assuming integer math, i.e. any remainders after division are lost?

Also, since rivers are counted, do I assume their underlying terrain is also counted?

[samson]

Thanks, Campo.

Solo, Your uranium save confirms something I saw the other day. I had a city that both supplied and demanded Gems. Gems was in the third slot in both the S and D lists. When I calculated all the SQs and DQs, there were only 2 commodities with Supply>Demand, which means (according to the model) that only two commodities should be on the Supply list. But this never happens. So Gems (even with an SQ of 0) was promoted to fill slot 3. I don't know if it was coindence that Gems was the 3rd high demand commodity.

In your game, I looked at Canton first and got the SQs and DQs of all commodities. Again only two commodities had non-zero SQs. And again, the 3rd slot Demand commodity was promoted to fill the 3rd supply slot also. In this case it was Uranium. The reason Uranium was 3rd in demand is because Copper has an essentially infinite SQ in MGE after a city reaches size 5. And Dye was in the second slot. Copper is demanded by almost every city in your game. And Dye is probably 2nd on the list almost everywhere but is frequently replaced by the wildcard.

[samson]

Just saw your last post.

You're doing it right. Yes, to all questions.

[samson]

Formula updates:

Silk Demand -- CitySize list corrected.
Silver Demand -- Spanish Civ modifier added.
Gold Supply -- special terrain rule added.


These corrections have been found in real game testing.