# The AI Re-Acceleration That Wasn’t

> Source: <https://paulkedrosky.com/the-ai-re-acceleration-that-wasnt/>
> Published: 2026-09-02 19:51:40+00:00

## What Happened

A recent analysis claims that AI model progress has sharply re-accelerated. Its evidence is the chart below, "showing" Epoch’s Capabilities Index rising from **8.3 points per year before 2024 to 15.5 points per year afterward**.

Here is the chart:

Epoch’s complete dataset is much less dramatic and exciting.

Here is the full chart:

So, what gives?

Well, I did the maths. And here is the answer: Using all ECI observations, and controlling for developer and model family, there is **no statistically significant breakpoint**. A piecewise model—which splits the series into intervals and applies a sub-function to each segment—does not improve on a purely linear trend: **p = 0.615**, The estimated change in slope has a confidence interval of **-8.4 to +23.4 points per year**.

In short, the maths shows there is no model acceleration, contrary to claims, and as expected. The result comes from **selecting frontier observations only, choosing a breakpoint, ignoring variance collapse, and fitting separate lines** on either side.

My [earlier work](https://paulkedrosky.com/why-400-hitters-disappeared-and-what-it-means-for-ai/) on the full composite shows the stronger underlying pattern: **rolling relative model gains have fallen from their 2024 peak, while model dispersion has narrowed sharply**.

### What It Means

**There is no evidence that model progress recently re-accelerated.**- The data are consistent with a continuing linear trend.