So I'm not exactly thrilled with how pop growth works atm.
Presently, there's a 'base pop growth', which is XML defined as a flat 0.2. Then everything which effects pop growth is done as a %.
This has a few silly consequences. First off, as near as I can tell the game doesn't record growth or population to a second decimal place. So if you get +10% growth, that's actually nothing (which is a problem when some techs are % growth bonuses). It also makes low-level hospitals pointless, too; they have a lifespan anyway as no full-pop colony needs them. Secondly, changing the number of colonists you send to a planet has no real impact on growth either; if you send 0.5 population to a planet it growth at 20% PER WEEK. Hand waving this away with 'migration' is a bit of a con when those migrants aren't really coming from anywhere early on - later, I suppose we can more or less get away with it, since we have all these other planets growing incredibly slowly. But in the very early game when you have 3 colonies and don't know anyone it makes no sense.
So I guess my question is... why is it this way round? Why isn't base growth handled as a percentage in the first place, as it logically should be? This would make sending out half-full colony ships into a genuine disadvantage, rather than a means of maximizing your growth quickly. And why does it only record population to 1 decimal place when adding any percentage modifiers actually requires it to record up to 3?