things affecting POP needs

[General WVPM]

I'm trying to understand how the needs for each POP is determined.
This is what I found so far:

• base needs is set in the <poptype>.txt file in .../poptypes/
  values are set per 250000 POPs
• Consciousness increases needs by a multiplier: 1 + con/10
  a con of 10, would mean double the needs, where as 0 con is normal
• need modifiers do not seem to work correctly, adding a +10% modifier doesn't do anything
  adding a -100% modifier does have an effect
• in .../common/defines.lua there is something called INVENTION_IMPACT_ON_DEMAND
  this only seems to affect everyday and luxury needs

As far as I understand it works something like this:
needs = Base * POP_size /250000 * (1+con/10) * (1+INVENTION_IMPACT_ON_DEMAND * number_of_inventions)

This formula is not accurate though and I'd like to know what other factors come into play and/or if any of the points I listed is incorrect.