This is a really interesting topic with lots of interesting points.
France is a really poor example case of a wealthy European country as its population growth was different (lower) than every other western country. Vicky 2 put in hardcoded stuff to lower French growth rate because no formula for Europe would fit Franc too.
I liked the idea of using world in data numbers to help work out what we should aim for. I have my own take on them though because I'd look at higher level country groupings to avoid some noise, and stop the numbers at 1914 rather than 1936 (death rates in 1914-1918 had very different causes to what is captured by SoL). War deaths are important, but we need a different mechanic to model them. I'll also leave America alone as the population growth there was less about natural growth and more about immigration, and that is a separate formula.
Pop of Europe 1836 = 255M
Pop of Europe 1914 = 448M
European growth = 75%
Pop of Africa 1836 = 96M
Pop of Africa 1914 = 146M
African growth = 52%
Pop of Asia 1836 = 803M
Pop of Asia 1914 = 1050M
Asian growth = 31%
This suggests to me that the higher SoL in Europe resulted in higher population growth rates as a general rule. Sure there were exceptions like France might be lower than 75%, but England was higher than 75%, and Ireland went up quickly before decreasing even faster. Ireland raises another point - the amount of emigration from Europe might make their underlying growth rate even higher. Also I'd guess that Asia may have been lower than Africa due to the impact in China of things like the Taiping rebellion and the Opium trade, while the slave trade had largely stopped holding Africa's growth back.
The impact of child labour laws is interesting. Currently in the game more advanced laws lower deaths. You are proposing to reverse the effect. Anecdotally your way makes sense to me, as I've heard high rates of child mortality are strongly correlated with high birth rates. Some rebalancing might be needed to make those laws still interesting choices (maybe buff the impact of education).
Food needs already increase much more slowly than luxury needs. This is what I'm seeing from the game\common\buy_packages\00_buy_packages.txt file.
Code:
wealth_10 = {
political_strength = 0.75
goods = {
popneed_simple_clothing = 50
popneed_crude_items = 43
popneed_basic_food = 133
popneed_heating = 26
popneed_household_items = 7
popneed_standard_clothing = 10
popneed_services = 23
popneed_intoxicants = 63
}
}
wealth_20 = {
political_strength = 18
goods = {
popneed_basic_food = 194
popneed_heating = 26
popneed_household_items = 134
popneed_standard_clothing = 126
popneed_services = 121
popneed_intoxicants = 84
popneed_luxury_drinks = 84
popneed_free_movement = 42
popneed_communication = 17
popneed_luxury_food = 8
popneed_luxury_items = 101
}
}
wealth_30 = {
political_strength = 88
goods = {
popneed_heating = 26
popneed_household_items = 207
popneed_standard_clothing = 161
popneed_services = 352
popneed_intoxicants = 216
popneed_luxury_drinks = 269
popneed_free_movement = 207
popneed_communication = 62
popneed_luxury_food = 269
popneed_luxury_items = 642
popneed_art = 21
}
}
At wealth 10 food is the biggest item by far, a bit less than half of the total (by eyeball). By wealth 20 it's still the largest but has dropped to under a quarter. By wealth 30 its switched from basic food to luxury food, but other things are 3 times larger, and food is closer to 10% of the total bundle.
This is the proper sort of breakdown this thread needs.
I've done a similar sort of look at historic numbers (1836-1936, though I take your point on the impact of WWI). Key points are:
Wealthy European Nations:
(UK, Germany, Italy, Begium, Netherlands)
Average 100 year change = 224%
Average yearly growth = 0.8%
Average wealth European and Middle Easter Nations:
(Turkey, Russia, Egypt, Iran, Bulgaria)
Average 100 year change = 244%
Average yearly growth = 0.9%
Poor Nations:
(China, Ethiopia, Madagascar, Cambodia, Niger)
Average 100 year change = 150%
Average yearly growth = 0.4%
(Out of interest, New World nations averaged 1200% change, obviously heavily skewed by migration. France has an anomalously low 118%, and poor old Ireland is at 36%, i.e. its population reduced to a third.
Now comparing this to in game growth, which is largely controlled by SoL.
Pop Growth effectively follows a trilinear curve between four points:
At SoL 1, growth = -2.9%
At SoL 8, growth = 0.0%
At SoL 20, growth = 1.7%
At SoL 30, growth = 1.2% (it reduces beyond this... but there are so few pops at SoL > 30 that it doesn't really matter.
SoL does a pretty good job at modelling the overall
trend of population growth, i.e. a rapid increase from poor pops, through to a peak at moderately wealthy pops (SoL20)), and a slow decrease beyond that. However in game growth is probably set at about
double historic level.
However, this is
significantly offset by the fact that the AI struggles to get Pops out of subsistence farms, so countries like Russia and Egypt have a heap of peasants sat on SoL 6 though 10... basically in the zero-growth borderline-starvation zone. This is probably unrealistically harsh for countries with an improving mass agricultural sector... but it is an underlying AI issue, rather than a population growth modelling one.
The game is also massively undercooking migration for this period... but that's another issue.