For what it is worth, here are some possible specs on length of Anarachy. Each factor has the possibility of adding turns to the time Anarchy exists.
Culture
Civ is in top 25% in Culture points (compared with other Civs) = 0 added turns
In next 25% = 1 added turn
In bottom 50% = 2 added turns
Military
Average of 5 or more units per city = 0 added turns
Average of 3-5 units per city = 1 added turn
Average of less than 3 units per city = 2 added turns
Gov type switching from - to.
Switching to Democracy or Republic from any other type = 0 turns added.
Switching to Communism or Monarchy from Dem or Rep = 1 turn added
Switching to Despotism from Com or Mon = 1 turn added
Switching to Des from Dem or Rep = 2 turns added
Starvation
More than 20% of cities facing starvation = 1 turn added
Happiness
Less than 1 in 10 citizens happy = 1 turn added.
Full upkeep must be paid for all buildings during period of Anarchy. Effect of city improvements halved.
Under those settings a civ switching from Monarchy to Democracy, who has 3.5 units per city, 1 in every 12 citizens happy, no starvation, and is 2nd highest for culture points in a 12 civ game would have Anarchy for 2 turns.
A civ switching from Dem to Com, with 5.5 units per city, 5th highest culture points in 16 civ game, lots of starvation but few happy citizens would have Anarchy for 4 turns.
Yes

No

???