### Author Topic: Understanding population growth  (Read 1267 times)

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#### Fifty

##### Understanding population growth
« on: December 29, 2014, 04:01:49 PM »
Hello, I was wondering if someone could give a slightly more technical explanation of the population growth mechanics. I know that increasing multipliers for goods, mail, pax, etc. will increase growth and that increasing the growth_factor_city etc. will decrease growth. However, my question is what specifically happens when you change these values.

Specifically, let's say I want to double the growth rate of a map. Can I just double one of these sets of numbers?

Also, can someone confirm that increasing bits_per_month leaves growth per month alone now? So, if I increase bits per month by 2, I would need to quadruple (2^2 = 4) growth to get back to "normal" growth per unit of game time?
Why do we park on the driveway and drive on the parkway?

#### DrSuperGood

##### Re: Understanding population growth
« Reply #1 on: December 29, 2014, 06:29:54 PM »
There are 3 factors that affects population growth utilization.
1. % passenger transported.
2. % mail transported.
3. % consumer satisfaction.

When all 3 are 100% maximum growth is obtained.

Mail is worth the least, followed by consumers and then passengers which is worth the most.

The rate of growth is based on certain tiers. Villages grow the slowest, struggling to gain more than a few people per month. Cities on the other hand (20k population odd) grow very fast easily reaching 100 growth per month or more.

From my observations on the server growth should be expected to be very slow since most tows are less than 1k people. However I am not sure if the 8 times month length is making them grow less per unit time than without. It also does not help that blue has a very inefficient passenger network and the other big passenger companies are fragmented networks (no exchange, not like blue would ever deliver many people to it unless he greatly improves his passenger network performance).

I have raised the issue that these mechanics need revision. Growth should be globally computed based on total world transport metrics and then allocated locally based on local transport metrics. Industry should then be allocated in the form of points with each new factory/power station/consumer deducting so many points from the counter. Industry growth should probably be linear with population (or maybe a slight decay?) while the population heads towards a limit when 100% of everything is shipped.

#### Fifty

##### Re: Understanding population growth
« Reply #2 on: December 29, 2014, 07:06:35 PM »
So, I basically understand everything you wrote above already. My question is very specific: how can I modify the settings to get n times the current population growth rate? A discussion about changing the way this works is fine, but I just want to know how it works right now more numerically.

Villages grow the slowest, struggling to gain more than a few people per month. Cities on the other hand (20k population odd) grow very fast easily reaching 100 growth per month or more.

I think it is the opposite, at least in percentage terms.

From my observations on the server growth should be expected to be very slow since most tows are less than 1k people. However I am not sure if the 8 times month length is making them grow less per unit time than without. It also does not help that blue has a very inefficient passenger network and the other big passenger companies are fragmented networks (no exchange, not like blue would ever deliver many people to it unless he greatly improves his passenger network performance).

I am pretty sure growth per unit game time is also reduced by a factor of 1/8. Just look at well-served industrial towns.
Why do we park on the driveway and drive on the parkway?

#### DrSuperGood

##### Re: Understanding population growth
« Reply #3 on: December 29, 2014, 09:35:00 PM »
I cleared this up with Fifty online.

There are 3 growth rates...
1. < 1,000
2. < 10,000
3. >= 10,000

Population growth does scale with month length. The result is about the same growth per month regardless of month length (so 8 times month length means 1/8 growth per unit of real time). We came to the conclusion the server will need growth rate adjusted to accommodate for the epic month lengths used so that people do not get bored however it will not bring it up to normal growth rate per month (as that would result in an insanely overbuilt map late game).

If months are too long there is a chance all growth could stop. This is because there is limited precision so if the month shift factor is larger than the precision an error will be introduced to growth which could possibly result in 0 growth at all for very large month shift amounts. However this is not a factor in the server and would only affect really insane month lengths.