Do Movie Sequels Always Get Worse?

The 5 Trajectories

We analyzed over 3,590 movie series using TMDB user ratings. By normalizing ratings against the first movie (Movie 1 = 0), we identified five qualitative trajectories:

Got Worse The "Icarus" Effect. These series start exceptionally high (Avg 6.54, far above the 5.94 global mean) and crash back to reality in Movie 2 (Avg 5.64).
Solid Defies Gravity. These start high (Avg 6.28) and stay high (Avg 6.25), making them the only group to statistically defy regression to the mean.
Got Better Regression Upwards. These series start poorly (Avg 5.63, well below average) but survive. Their "improvement" is often just a return to the mean.
Bounced Back Starts strong (Avg 6.24), stumbles in the sequel (Avg 5.81), but manages to recover quality in later entries.
Lost Steam Starts average (Avg 6.02) and rises briefly, but eventually succumbs to the trend and crashes in later movies.

Is this Regression to the Mean?

Probably.

Sequels are typically only produced for successful movies. This creates a selection bias where Movie 1 is almost always "above average." Movie 2, lacking this filter, tends to return to the statistical baseline. Statistically, this effect is enough to explain the "Sequels get worse" observation.

Global Average
(All Movies)

5.94

Baseline

Movie 1
(Starter)

6.29

Significant
(Z=21.1)

Movie 2
(Sequel)

5.98

Normal
(Z=2.5)

About the Data

Ratings are based on the User Vote Average (0-10) from The Movie Database (TMDB), a community-built open database. We analyzed 3,590+ franchises with at least 2 movies.