Puzzled by SetAttributes:: Income column

This is an offshoot from my recent thread about Church Tithes . With that tweak, I managed to get the income-reduction effect I was seeking but the amount of reduction was somewhat unexpected (I'll discuss the details of this in the other thread). After much tapping on the old calculator, I resorted to looking at the Era file, to get the 'true' base income value for my test province (Wessex).

I was surprised by what I found (or rather what I hadn't properly noticed on previous occasions), hence this post.

I have, in the past, activated Sahara and used it as a revenue-generator for the rebels. I set it at 10000 and basically thought no more about it, as I was really focusing on other aspects. I saw it with income in the 9000's, one time and 14000's at another but put this down to governor-acumen effects, or things they'd built, at the time.

Only now do I realize what is really going on here.

Back to Wessex, for the moment.

The Era file sets Wessex base income at "350".

On turn one (1087) of English:Early:-
King's Acumen=4 (applies to all values, shown below, equally and thus disregarded in calculations)
Wessex Tax rate = Normal
Governor = None
Improved Farmland = None
Income = 196     :inquisitive:

After assigning an Acumen_4 Governor and setting V_High taxes (125%)
Income = 342 ...which is (very nearly) {196 x 1.4 x 1.25}

Not quite 350, but close, all the same.

After making the governor Chamberlain (+2 Acumen), making him Acumen_6
Income = 392 ...which is (precisely) {196 x 1.6 x 1.25}

I built the trading post before the Church, to see if it would be affected by my income adjuster tweak and it generated 32 (Local trade only)

Before Church: Wessex Income = 424 (Farms = 392)

After Church: Income = 378 (Farms = 346)

So the Trading post was unaffected.

The true farm-income reduction is 346/392 = 0.882 or 88%, whereas I wanted it to be 90% (the value I'd set in the BUILD_PROD file). Curiously, the reduction ratio isn't identical for various other tax rates but that's for discussion back in the other thread.

For now, I'm just curious as to why the SetAttributes:: Income level equates to that only attainable with an Acumen_4 governor and tax rates set to Very High?

We're accustomed to routinely saying "each acumen feather is a 10% boost" but my findings seem to indicate that, closer to the truth, would be to say that Acumen_4 is "normal"; above 4 is +10%, +20% etc.; below 4 is -10%, -20% etc. "Ungoverned" actually works out to be 56% of the SetAttributes:: income setting, or "-44%" - if you want to look at it that way (at Tax=Normal).

Anyway, it's wierd that the program back-calculates the "ungoverned" value, rather than start with a base figure and apply various modifiers to that.