The Galwiki has the following info in regards to planet influence:
On the galaxy main map, selecting a planet will reveal that planet's influence level (shown as IP points). In parentheses next to your IP level is the relative foreign influence calculation. If that number is greater than 4, your planet may culturally revolt. If your espionage level is high enough, you can see whether or not another civilization's planet is close to defection.
Shouldn't the, "If that number is greater than 4" read, "If that number is greater than 4X the planet's generated influence"