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unmerged(11202)

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Oct 4, 2002
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Having too much time on my hands and being rather curious on what the effects and workings are of growth rates in the long run in EU2, I have made the following analysis.

The province population growth percentage expresses the growth on the basis of a decade because otherwise you get really small percentages.
A handsoff game has lead me to the following observation, the game actually calculates the population growth on a monthly basis for a province. This monthly increase is determined by the percentage given for the province divided by 120, the number of months in a decade. A province that has a growth rate of 12% will have the following monthly growth rate: 12/120=0.1% per month. Over the course of a decade this leads to the following population increase factor: (1+0.001)^120=1.127.
In the handsoff game this was confirmed. Starting with a province of 1000 inhabitants with a growth rate of 12%, I ended up with 1127 inhabitants after exactly 10 years of gameplay. Now if growth was based on a decade basis a population of only 1200 would be expected after a decade.
Take notice of the effects of compounding, like with interest that accumulates on a bank's deposit account. When growth is determined on a monthly instead of yearly, or in this case decade's basis significant differences can emerge.

I will now express the general formula for the increase of population used in EU2:

P(end) = P(start)*(1 + (PGR/120)/100))^n

P(end) = Population at the end of the period in the province.
P(start) = Population at the start of the period in the province.
PGR = Province Growth Rate, this is given in the view province screen.
n = The number of months over which you wish to calculate growth of the province population.

Given the abovementioned observation the formula yields the following result: 1000*(1+(12/120/100))^120=1127.42
Being rounded to an integer value this fits the observation nicely

Now how is the growth rate determined? The following factors are of influence:
- Stability: giving a range from +1% growth at -3 stab till +7% growth at +3 stab, each additional stab point thus increases growth rate with 1 percentage point.
- The colony modifier: this is a +5% additional growth, this applies for any province not having reached the 5000 inhabitants yet.
- The Center of Trade Modifier: +5% for any province that has a CoT in it, for provinces neighboring a CoT this modifier is +2%.
- The Governor: + 1% for any province in which a major is promoted to a governor.
[edit, I forgot to add that a manufactory gives +2% growth as well]
- Then there is also a fixed penalty for a province which can vary from -1% till -14%. This penalty will decrease at certain population levels, 1000, 2000 and it will disappear completely at 5000 inhabitants. Nations that have their capital on the same continent/region as the province that is penalized don't receive a growth penalty. For example African nations will not suffer any growth penalties in African Colonies.
The other penalties are due to war/rebel related activities
- 3% of having a province occupied by an enemy force, this is when someone else has taken over control of your province.
- 5% when a province is looted, happens when an enemy army is in the province at the end of the month, the effect lasts for 13 months.
- 5% when a province is under siege.
- 5% if enemy troops are currently present in the province.
I have drawn up the following table which shows the growth factors over the long run at different growth rates. The lefthand collumn gives the growth percentages and the upper row the number of years.

Code:
 [FONT=courier new] [COLOR=white]
%\years	10	50	100	150	200	250	300	400
-12	0,89	0,55	0,30	0,17	0,09	0,05	0,03	0,01
-11	0,90	0,58	0,33	0,19	0,11	0,06	0,04	0,01
-10	0,90	0,61	0,37	0,22	0,14	0,08	0,05	0,02
-9	0,91	0,64	0,41	0,26	0,17	0,11	0,07	0,03
-8	0,92	0,67	0,45	0,30	0,20	0,14	0,09	0,04
-7	0,93	0,70	0,50	0,35	0,25	0,17	0,12	0,06
-6	0,94	0,74	0,55	0,41	0,30	0,22	0,17	0,09
-5	0,95	0,78	0,61	0,47	0,37	0,29	0,22	0,14
-4	0,96	0,82	0,67	0,55	0,45	0,37	0,30	0,20
-3	0,97	0,86	0,74	0,64	0,55	0,47	0,41	0,30
-2	0,98	0,90	0,82	0,74	0,67	0,61	0,55	0,45
-1	0,99	0,95	0,90	0,86	0,82	0,78	0,74	0,67
0	1,00	1,00	1,00	1,00	1,00	1,00	1,00	1,00
1	1,01	1,05	1,11	1,16	1,22	1,28	1,35	1,49
2	1,02	1,11	1,22	1,35	1,49	1,65	1,82	2,23
3	1,03	1,16	1,35	1,57	1,82	2,12	2,46	3,32
4	1,04	1,22	1,49	1,82	2,23	2,72	3,32	4,95
5	1,05	1,28	1,65	2,12	2,72	3,49	4,48	7,39
6	1,06	1,35	1,82	2,46	3,32	4,48	6,05	11,02
7	1,07	1,42	2,01	2,86	4,05	5,75	8,16	16,43
8	1,08	1,49	2,22	3,32	4,95	7,38	11,01	24,51
9	1,09	1,57	2,46	3,86	6,05	9,48	14,86	36,55
10	1,11	1,65	2,72	4,48	7,38	12,17	20,06	54,51
11	1,12	1,73	3,00	5,20	9,02	15,62	27,07	81,29
12	1,13	1,82	3,32	6,04	11,01	20,06	36,53	121,22
13	1,14	1,91	3,67	7,02	13,44	25,75	49,30	180,76
14	1,15	2,01	4,05	8,16	16,42	33,05	66,52	269,55
15	1,16	2,12	4,48	9,47	20,05	42,42	89,76	401,92
16	1,17	2,22	4,95	11,01	24,48	54,45	121,12	599,28
17	1,19	2,34	5,47	12,78	29,89	69,89	163,43	893,54
18	1,20	2,46	6,04	14,85	36,50	89,71	220,51	1332,22
[/COLOR] [/FONT]

Please note that the growthfactors in the lower right corner should be ignored, since at 5000 inhabitants the colony bonus disappears, 13% is the maximum possible percentage afterwards.

Studying this table I have noticed the following at what I estimated as the standard growth percentage of about 4%, leaving some margin for stab losses and wars which cause lower growth then the default 7% at +3 stab at which I run my nations most of the time. Over the entire EU2 period this would mean a that your population increases by a almost a factor 5. Compared with the growth of the world population during the EU2 history this very high. The world population grew at a much lower average rate of annually 0.0025% giving a growth factor of 2.17.
Now I know that the population of a province represents only that of the most important city and that populations of those cities tended to grow at a higher rate due to migration to the cities. But in EU2 this rate still too high IMHO especially when the CoT bonus is taken into account. I had a colony as portugal in India in the early 15th century with the natives having joined the population. Around 1550 I got a random CoT popping up, after 200 years in 1750 the population had reached a staggering 150.000.
Concluding, I would propose to make some cuts in the growth percentages of provinces. Firstly to cut the base growth rate by stability in half, each additional stab point should only give a o.5% increase instead of 1%. Secondly reduce the CoT presence bonus, propably cutting it back to 2% or 3% and 1% for neighboring provinces.
Overall the average growth rate in a province should be around 2.5%-3.5%, it should start out a 2.5% in the beginning of the game and increase as the game progresses. This can be achieved by increasing growth rate with 0.1% for each infrastructure tech level.
I am not too sure about the precise effects in the game, escpecially when it comes to the tax gains from a province which depend to a large extend on the population size. Perhaps the size population brackets for the taxvalues should be decreased. Also a higher number of population tax brackets would required to make more populous provinces profit from their bigger populations.

This is rather a long post and I may have made some errors especially since I wrote a great part of it last night. I may carry out some changes later on. ;)

[edit] Drats, that table looked really nice in a texteditor, I wish I knew how to get it more tidy. :( :confused:
 
Last edited:

Castellon

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Originally posted by Alkar

[edit] Drats, that table looked really nice in a texteditor, I wish I knew how to get it more tidy. :( :confused:

Use the code tag and courier new font tag.
 

SJG

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Dividing the decade growth rate by 120 to get the monthly growth rate is a reasonable approximation when growth rates are small. To get the actual growth rate you should do a 120th root ie (1.07^(1/120) at 7%) which is a nasty and processor hungry calculation. At small numbers the compound amount is usually small enough to ignore without sacrificing too much accuracy.

By coincidence I was looking at population growth figure in Europe over the course of the middle ages and I observed that population is estimated to have grown by 15% between 1400 and 1450 and a similar amount between 1450 and 1500, that is approximately 3% per decade. Given that stability is not always meant to be +3 and there are various factors that affect the growth rate downwards (more than effect it upwards) the conclusion is that EU2 isn't a bad approximation of reality and doesn't need changing.

--- EDIT ---

Some numbers.

If the percentage growth rate is expressed as a decimal x (between 0 and 1) then the excess is represented by

Actual growth - expected growth

=(1+x/120))^120 - (1+x)

Using the binomial expansion this can be expressed as:

-(1+x)+1+x+120*119/2*(x/120)^2+120*119*118/6*(x/120)^3+...

(approx)= 0.496x^2+0.163x^3+...

I think this is right (it's been a while since I did any maths)

As x is small it is not significant.
 
Last edited:
Dec 11, 2001
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Well, I do think that the growth rate shouldn’t be the same at the beginning and the end of the game.

I like the idea that it should be attached to the infra level.
 

SJG

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Growth rates increase with manufactories, which are more common later in the game, and governors, which can only be built after infra 5 is reached. There are also more COTs at the end of the game, which affect not only their province but any neighbouring provinces.

All of these mean the growth rate at the end of the game is higher than at the beginning. Is it enough of an increase? I don't know, I doubt it. But then population is almost irrelevant after a certain point is reached.
 

unmerged(9214)

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May 7, 2002
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A while ago I made some statistics about city growth. It appears that there is a limit of about 2500 inhabitants/year once the city reaches certain population (my estimate 200 000).

(Edit: Make that 200 000 and not 657 000.)

Here are yearly growth rates of four somewhat comparable cities. What it doesn´t show is that my goal as Denmark was to make Lübeck the greatest city in the world and I had to sack the others every now and then.

__Year__Genova__Paris__Venezia__Lübeck
1419-1429 1,17 % 1,11 % 1,26 % 1,06 %
1429-1450 1,21 % 0,97 % 1,18 % 1,16 %
1450-1480 0,98 % 1,07 % 1,19 % 1,29 %
1480-1505 1,23 % 1,17 % 1,25 % 1,43 %
1505-1515 1,17 % 1,01 % 1,13 % 1,24 %
1515-1554 0,97 % 1,06 % 1,09 % 1,34 %
1554-1576 0,82 % 0,83 % 0,80 % 1,10 %
1576-1594 0,70 % 0,69 % 0,72 % 0,90 %
1594-1640 0,58 % 0,65 % 0,58 % 0,71 %
1640-1660 0,49 % 0,54 % 0,48 % 0,58 %
1660-1736 0,38 % 0,42 % 0,38 % 0,45 %
1736-1740 -0,21 % 0,07 % -0,17 % 0,38 %
1740-1744 0,00 % 0,00 % 0,03 % 0,37 %

I have actually statistics for 14 big cities, but it is rather cumbersome to show it here.

Now it´s time to some calculations with that new formula.:D
 
Last edited:

unmerged(9214)

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Originally posted by Alkar

I will now express the general formula for the increase of population used in EU2:

P(end) = P(start)*(1 + (PGR/120)/100))^n

P(end) = Population at the end of the period in the province.
P(start) = Population at the start of the period in the province.
PGR = Province Growth Rate, this is given in the view province screen.
n = The number of months over which you wish to calculate growth of the province population.
Tried Your formula, but it looks like it doesn´t work over long timeperiods as it doesn´t address the 2500/year growth limit. For shorter period and smaller cities it may well be correct.
 

unmerged(9214)

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OK, now this shows population in thousands in certain roughly comparable cities. Hope it´ll give some data for further calculations. :)


Code:
 [FONT=courier new] [COLOR=white]
	Bologna	Rome	Shang.	Kyoto	Edo	Beij.	Antwer.
1419	55	80	50	70	60	100	37
1429	59	86	56	77	68	106	40
1450	68	99	72	86	90	122	51
1480	84	123	101	89	87	149	73
1505	100	149	137	119	104	177	98
1515	107	163	153	128	110	189	110
1554	138	228	230	182	144	242	164
1576	161	278	288	236	176	279	195
1594	183	324	335	282	207	303	240
1640	252	441	434	396	309	365	360
1660	287	492	443	447	362	390	412
1736	431	683	586	645	564	534	595
1740	420	693	597	656	575	544	606
1744	426	704	597	666	586	555	616

	Paris	London	Venézia	Genova	Lübeck	Tenoch.	Const.
1419	60	40	60	65	36	40	100
1429	67	42	68	73	40	45	107
1450	82	47	87	94	51	58	114
1480	113	56	124	126	75	83	147
1505	151	65	169	171	107	113	190
1515	167	68	189	192	121	128	200
1554	252	88	288	280	203	202	285
1576	302	110	343	335	258	257	329
1594	342	132	390	380	303	302	336
1640	460	203	509	496	419	415	456
1660	512	239	560	547	470	461	507
1736	702	422	745	728	661	646	672
1740	704	433	740	722	671	656	682
1744	704	443	741	722	681	666	693


[/COLOR] [/FONT]
 

unmerged(10355)

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Jul 24, 2002
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You forgot about the population growth cap where, regardless of the rate of change, a province's population cannot increase by more than 210 in any particular month.