Psychotic Weasel posted:

I can't really draw up a chart on my phone but every pop starts at 50% Happiness without any other modifiers. From there anything above 60% or below 40% will begin to accumulate a bonus or penalty to what they produce, an impact on unrest and their attraction to ethics. I think the most is still +20% for maximum happiness and depending on what is making a pop unhappy (like if you're purging them or they're starving or rebelling) production can drop to 0. Most of the time it'll bottom out around -20% I think but rarely see that unless you have a very angry faction people are joining.

Slaves, robots, unliberated AIs, hiveminds and nerve stapled pops are not affected by happiness.

Edit: if you hover the happiness bar on any pop it will tell you exactly what is impacting what. Same go for hovering over the resource number for each tile, it will list everything impacting output.

Long story short with happiness: more = better, less = less better. That's all that really matters.

If you want to get technical you can go through and cost out what various edicts and policies will cost you vs. their impact on your pop's output but most of the time I find it doesn't matyer. I do not min/max this game in anyway so YMMV.