Have AI Capabilities Accelerated?

Epoch AI's analysis finds that AI capabilities have recently accelerated on three of four measured metrics—ECI, the log of METR's 50% time horizon, and a composite Math Index—linked temporally to the rollout of "reasoning" models in 2024. The best single explanatory fit for these three metrics was a reasoning/non‑reasoning split: reasoning models show a discrete level jump plus roughly 2–3× steeper linear progress versus non‑reasoning models, although several other superlinear fits also perform well. The Combined Math Index was produced via a 2PL IRT fit across multiple math benchmarks (ridge penalties λa=0.378, λb=0.0001) and rescaled to map Sonnet 3.5→130 and GPT‑5→150. The study fit eight parametric curves by unweighted least squares and evaluated them with expanding‑window cross‑validation (primary horizon = 6 months), plus leave‑one‑out/contiguous‑block perturbation checks to assess stability. WeirdML V2 showed no acceleration, possibly because of task constraints and limited pre‑2024 data; authors caution the acceleration may be concentrated in domains—programming and math—where correctness is easily auto‑verified and RL has been heavily applied.