The Porter Ratio (Quinn Porter, AHQ papers) is R = λ_self / λ_env.
λ_self is the rate of internal structure restoration and propagation.
λ_env is the rate of environmental disruption.

When R ≥ R★ (the ostiary/coherence threshold), prior states remain active, forming a self-sustaining interior with temporal depth and recursive coherence. Below it, structure dissipates and the system stays externally driven.

Primary sources:
https://philarchive.org/rec/PORATT-2
https://philarchive.org/rec/PORTCT-15

Some obvious similarities to Hoverstadt’s: “to survive, the system must be capable of a rate of change that is greater than or equal to the rate of change in the environment on which it depends”: ΔS ≥ ΔE. (Grammar of Systems, 2022)

(he also says the strategies to achieve this include moving faster, retarding the environmental change rate, or directing environmental change)

See

https://researchgate.net/profile/Patrick-Hoverstadt/publication/332082232_Organisational_agility_and_its_measurement/links/5c9e5a9da6fdccd460438dae/Organisational-agility-and-its-measurement.pdf?utm_source=chatgpt.com&__cf_chl_rt_tk=PIder.UzjUOsdZLeNwyBUII3oE1kRQb3Sc7_6SoFK7E-1786986626-1.0.1.1-E2LwoKpdqyPkvzAMkczO8p92KOHOQ5zW0hRzdRDJOJM (2018)

https://mesg.ch/en/organisational-agility/ (2021)

https://systemspractice.org/system/files/2022-03/2022.2%20hoverstadt.pdf (2022)

The 2018 measurement paper and 2021 MESG piece turn ΔS ≥ ΔE into a practical diagnostic: quantify environmental change rate, then assess scanning, orientation, decision speed and pivot capacity. Those levers directly raise the effective internal rate, matching the three strategies and the quantitative Porter threshold.