Crusade or base game?  In Crusade, the population contribution to a planet's raw production is equal to the square root of the population.  If I remember correctly, in the base game it was equal to the population.

There is a population discussion over at the Steam forum where Frogboy made a suggestion how pop could work since a lot of people are not content with the square root formula.

I quote Frogboy here:

"I almost think what we should do is something like this:

Population = Production points.

and then you balance things around making population harder to increase.

So Earth, for example, has 7 (7 billion).

A new colony would have a pop cap of say 1 until you add cities which can increase them by a relatively small amount but.

The problem with having it be some exponent is that it's not intuitive to the player.

Thoughts?"

Here is what I would suggest (I made a suggestion elsewhere that buildings should need pop to work, but that doesn't prevent me from having other ideas ):

- Make 1 pop = 1 production, but only in one area. Make it so that you can move your pop between the four areas ship production, social production, research and wealth. Let the player configure a distribution ratio for those four areas so that new pop is distributed automatically according to the respective ratio and no user interaction is necessary every time. There you have back your wheel

- But: you cannot move people around as you wish! You cannot put a trained scientist to work as a bank accountant. So if you want to adjust existing production priorities you have to fetch those bank accountants from other planets where they already work in the economy, and that you have to do with mini freighters (which are attackable and need some time to reach their target.

- Population growth should not be linear, it should depend on your current population and available living quarters (aka pop cap). So let the growth factor be something like (x * Morale * (1 - current pop / pop cap)) %, the actual factor for x could depend on race traits and morale improvements. And example with x = 5, morale = 75%, current pop = 3, pop cap = 10:

Growth = 5 * 0.75 * (1 - 3 / 10) % = 5 * 0.75 * 0.7 % = 2.625 %, so pop would increase by 2.625 % * 3 = 0.07875 this turn.

That would also prevent colonizing planets with nearly empty colony ships because growth would take much too long.

I'm not a fan of square rooting the population, but I understand the point of diminishing returns as population goes up.  I think taxes and influence should stay linear with population, but apply diminishing returns to productivity; the idea being that benevolent ideologies are marked by high approvals, and ungodly high populations which do most of the work.  They exude money and influence.  Malevolent races just slash-and-burn, produce military, and they have to get their population by enslaving the benevolent races, who were able to grow their populations.   Population needs to matter again.

The idea is, benevolents struggle with productivity, so they have to buy it.  Or wage influence wars, without firing a shot.  Malevolents are fine with productivity, but they lack the population to take advantage of it, and have to go out and get it.  But they are vulnerable to the benevolents flipping them; and if they do, they sure have no problem leveraging that factory capacity.