So I'm nearing the end of my Beginner tutorial playthrough, and I think I understand all the basics of how to setup trade routes and how to manage them.  Now I want to get into the nitty gritty of exactly what's going on under the hood so I can make choices about which systems to build HQs / subsidiaries on, etc.

I haven't been able to find many concrete details, although this excellent video did some good testing and gave some great insights into most of it.

When I look at a system with the System Management Scan (spacebar), I can see some details such as:

• Trade efficiency, which seems to displays "Neighbors count," or number of adjacent systems which are colonized (whether colonized by you or a different major faction, as I discovered)
• Trade output, which displays how much of a bonus to Food & Industry this system gets for being along a trade route (I was surprised that trade routes affect these at all).
• A pie chart which display the "Trade quality rating"

So here are my questions:

• Trade efficiency - Does anybody know how this affects the trade route?  The video mentioned that for Trade HQs and subsidiaries, they will take a % of all adjacent systems Dust/Science/Luxuries and add the value to the trade route (and apply the bonus Food & Industry on neighboring systems), but I did not see any evidence of that happening in my game as it did in the video.  Perhaps it functions differently in the tutorial, as several other game mechanics seem to.  If it does work like that outside the tutorial, does the same apply to systems that are merely along a route?  Is the bonus just a raw % of these adjacent systems, or is there some bonus multipler for the total # of colonized adjacent systems, regardless of the wealth in those systems?  UPDATE: It seems like when playing a non-tutorial game, the trade routes are properly taking some dust / luxuries from adjacent systems, I think?
• Trade output - I see that I get a little bonus to Food and Industry on systems along a trade route, although I don't believe it was ever mentioned in the tutorial.  In my case I get +1.7 to each.  Does anybody know where this 1.7 figure comes from, and what factors will make it increase (or decrease)?
• Trade quality rating - What does this signify?  What is the game evaluating in order to determine whether a system gets a "high" or "low" quality rating?  How does it affect the value of the trade route?
• What determines the Dust/Science value for different systems when looking at the Economy Scan (Spacebar) on the Galaxy Map?   I've almost got this one figured out.  The video suggests that the main factor is just the total population in the system, which seems to hold true for me in general.  In my current game, almost every system has a Dust value of exactly 0.2 x system population.  My systems with a trade Hq / subsidiary get a +5 bonus as described in the video.  The only thing I can't figure out is why two of my systems have a value of 0.5 x system population instead.  I thought possibly since those systems have less adjacent colonies, but even my completely isolated colony floating in space gets the 0.2 x value, and the other systems it didn't matter whether they had 2 or 3 adjacent colonies.
  • UPDATE: OK I think I have this one cracked.  Looks like the formula is System Trade Dust = (0.1 x system population) x system colony level [+ 5 if Trade HQ / Subsidiary present].

Sorry for the wall of text and thanks in advance for any knowledge shared!