Which one is correct?

The Datalinks of the game itself, say +1 Efficiency. So that's what I'm going with, unless someone has proof of a bug or the Datalinks themselves being wrong.

Also does this efficiency modifier affects both inefficiency and b-drones? I would understand it affecting inefficiency since each base inefficiency is calculated independently. So you just modify Efficiency value in the formula. However, it's not that intuitive with b-drones since they are defined by NUMBER of bases above threshold. Also additional drones are distributed across all bases more or less equally. So what if one of the bases has Children's Creche? How does it affect b-drones formula?

By "b-drone" I take it you mean a drone that appears due to Bureaucracy. Such drones are

*not *distributed across bases "more or less equally". They are distributed

*randomly*, in as many cities as you are above the Bureaucracy threshold. They could appear in a city that has plenty of happiness and you don't basically notice. They could appear in a city that's not so well developed and you get an immediate drone riot. The effect you usually experience as a player, is when you settle a new city, you

*often *get a drone riot in one of your old cities,

*at random*.

I doubt that individual Children's Creches affect the global formula. I bet it keeps one of those drone riots from happening at that specific base. However I could be wrong. Conceivably,

*all *of the Children's Creches could be added up to determine some kind of ultimate Efficiency. I haven't studied the game binary so I don't know exactly how it works.

The way I see it, a Children's Creche costs 1 energy to maintain. If you are losing 1 energy due to inefficiency, it's a break even / worth doing. Assuming you don't have something more important to build.

The real need for a Children's Creche, IMO, is when you want to trigger a population boom. That +2 GROWTH is really important, as you need to get +6 GROWTH to get a pop boom in a city. Maybe if you get everyone into a Golden Age you can do it that way instead, but getting your global GROWTH up to +4, then building Children's Creches, is reliable. In my mod, +4 is as high as you can make global GROWTH, so Children's Creches are pretty much essential.

A Children's Creche also gives a defensive MORALE bonus and reduces a base's vulnerability to enemy mind control.