Public Opinion
Public Opinion reflects the overall opinion of the typical residents of a given nation, or of Earth generally. Having high public opinion gives a significant boost to a faction, as a built-in source of free 
Influence and as a bonus on a wide variety of missions. Public opinion can be changed in a wide variety of ways, either positive (such as performing Public Campaign missions) or negative (such as committing atrocities).
Public Opinion Effects
Public support for a faction provides many benefits, including but not limited to:
Influence Income
For every one million supporters a faction possesses, their annual Influence income is increased by 0.5. This bonus applies even if the faction does not possess any of the nation's control points.
On a planet of 8 billion people, each 1% global support gives 40 influence per year, or 3.33 per month.
Councilor Mission Support
Most councilor missions that attempt to gain or maintain control of the nation have mission modifiers based on the nation's public opinion. Public support for a faction makes such missions significantly easier for them, and significantly harder against them. This is especially true in highly democratic nations.
Specifically, the mission modifier has X points, where X = (10 + 
Government) * public support fraction for the faction.
Preventing Organic Coups
In very rare cases, high Corruption in a nation can lead its elites to organically launch a coup even without outside intervention, if they are not sufficiently appeased by investments into the 
Spoils priority. But high public support (>65%) for the faction that owns the nation automatically prevents such organic coups from occurring.
Post-Revolution Changes
Whenever a revolution occurs in a human nation, public support for the old control point owners is compared to public support for the new control point owners. If the new owners are significantly more popular with the public, the nation can experience large benefits: increased 
Cohesion, reduced 
Unrest, and reduced 
Inequality.
Base Cohesion
Public opinion affects the Base Cohesion of a nation in two ways.
First, Factions that own a nation will find the nation to be significantly less cohesive when the public does not support them. This is represented as an X point penalty to the nation's Base Cohesion, where X is twice the ideological distance between the average ideology of the factions that own the nation's control points and the population-weighted average ideology of the public. (Note: ideological distance is calculated using good old pythagoras.)
Second, a public with wildly differing views is naturally far less cohesive than a public that bands together to support one ideology. This is represented as an X point penalty to the nation's Base Cohesion, where X is calculated as follows:
- 1. Set X to be the public opinion's standard deviation.
- 2. Divide X by the worst possible standard deviation (this is when the two most different ideologies are each supported by exactly half the public).
- 3. Subtract 0.5 from X.
- 4. Multiply X by 6.
Note: X can actually be negative, meaning that the Base Cohesion can actually be increased by a highly unified public opinion.
Changing Public Opinion
Any effect that changes public opinion is collectively known as "propaganda", and has a propaganda value. Each piece of propaganda is defined by two things: the faction ideology it is aimed at, and the strength of the propaganda. For example, a typical public campaign mission applies Propaganda for the councilor's faction, with a base strength of roughly 10.
Propaganda values can also be negative, reflecting things that drive the public away from a specific ideology.
How Propaganda Works
Whenever Propaganda of strength X for a faction F is applied on a nation, the 
Population of the nation is split into roughly (Population / 100) ^ 0.5 groups, where each group fully supports one ideology. Then for each group, a random value Y between 0 and 100 is rolled, and then:
- Nothing happens if any of the following are true:
- X >= 0 and the group already supports faction F. Because this is just preaching to the choir.
- X < 0 and the group does not support faction F.
- Y > X and Y > -X, indicating that the propaganda failed to convince the group.
- Otherwise:
- If X >= 0, then:
- If X - Y > 10, the group's ideology moves towards F's ideology by 2 units, then moves to the closest matching ideology.
- Otherwise, the group's ideology moves towards F's ideology by 1 unit, then moves to the closest matching ideology.
- If X < 0, then a completely random coordinate is selected from within a cube of length 2 that is centered on the group's original ideology, and then:
- If (-X) - Y > 10, the group's ideology moves towards the coordinate by 2 units, then moves to the closest matching ideology.
- Otherwise, the group's ideology moves towards the coordinate by 1 unit, then moves to the closest matching ideology.
- If X >= 0, then:
Public Support Cap
Within each nation, the public support for any faction is capped at (90 - Government + Cohesion)%. But this cap is implemented in a somewhat counter-intuitive manner: whenever a propaganda is about to be applied, the game will first check if any faction's public support has surpassed the cap. If so, then during the application of the propaganda, every attempt by a Population group to move to the closest matching ideology will behave as if the capped faction's ideology does not exist.
Consequently, once a faction goes over the public support cap, it can no longer gain public support from any kind of propaganda. But if a faction is below the public support cap, there is nothing preventing it from gaining enough public support from one propaganda application to far exceed the public support cap.
Sources of Positive Propaganda
These include but are not limited to:
A Successful Councilor Public Campaign
Applies propaganda for the councilor's faction with strength X, where X is calculated as:
| 10 | Base Value. | ||
| ×2 | On critical success. | ||
| Up to +9 | Earth Interface Hab Module bonus (Broadcast Outlets, Communications Hubs, and Media Centers.) | ||
| ×1.15 | Project Research: Appeals to Hope Messaging (Available to  The Resistance,  Project Exodus, and  The Academy.)
| ||
| ×1.25 | Project Research: Appeals to Fear Messaging (Available to  Humanity First,  The Initiative,  The Protectorate, and  The Servants.)
| ||
| ×1.25 | Project Research:
(Available to | ||
| -3.5 to +3.5 | Random. |
A Unity Priority Completion
Each completion of 
Unity Priority applies propaganda for each faction that owns any of the nation's control points. (Empty control points do not count.)
Propaganda strength is 5 multiplied by the number of control points owned by the faction, but the Religion control point counts as 4 control points. Abandoned or 
Cracked control points do not count.
Propaganda strength is also affected by Population Scaling.
Note: Ordering matters. The last faction to get propaganda applied on each unity completion would get more public support and influence income on average.
The ordering here is determined by the control point ownership: the faction that owns the leftmost control point goes first, then the faction that owns the leftmost control point that isn't controlled by the previous faction, then the faction that owns the leftmost control point that isn't controlled by the previous factions, and so on. Thus when sharing nations with other factions, one should try to avoid owning the leftmost control points.
A Martyr Councilor Killed
If a councillor with the Martyr trait dies violently, it applies propaganda for the councilor's faction on every nation.
Propaganda strength is 35.
Publicize Alien Threat Researched
Applies propaganda with strength 10 for the faction responsible on every nation.
Available to Humanity First, The Resistance, and Project Exodus.
Sources of Negative Propaganda
These include but are not limited to:
A Spoils Priority Completion
Applies propaganda for each faction that owns any of the nation's control points.
Propaganda strength is (
Education + Government) multiplied by -0.125 multiplied by the fraction of the nation's control points owned by the faction.
An Army Destroyed
Applies propaganda for the faction that controlled the army on the home nation of the army.
Propaganda strength is Government multiplied by -1.
An Atrocity Committed
Applies propaganda with strength X for the faction responsible on every nation, where X is calculated as:
- Set X to the total number of atrocities committed by the faction, including the newest atrocity.
- Multiply X by -0.333.
- Divide X by 2 if Total War Framing has been researched. (Available to
Humanity First, 
The Initiative, and 
The Servants.)
Game Text
The people of Earth all hold a particular viewpoint about the alien arrival. But people are malleable, and events and propaganda can sway them to a different point of view.
These viewpoints track with the ideologies of each faction, along with an "undecided" viewpoint in the middle of all of them. Ideologies have a position relative to each other; when events have a chance to change someone's opinion, they will typically move to something nearby -- a Resistance supporter could see their views radicalize to those of Humanity First, or soften to being simply undecided, for example.
Public support for your faction is a primary source of the influence resource. You will also receive bonuses on missions in nations where a large portion of the public is on your side.
A potential mover of public opinion are atrocities committed by a faction. Atrocities are actions that cause mass death or suffering, and responsible factions suffer the loss of supporters as a result. Atrocities are cumulative; as a faction commits more, the public opinion penalty increases dramatically.
~ Terra Invicta Codex, 0.4.85.
