Metric · Hooked
Unprompted session share
Share of sessions that start with no external trigger and no message delivered in the prior 30-60 minutes, by tenure cohort. The behavioral proxy for internal triggers: it should rise as users stay longer.
Plain label: sessions nobody promptedAlso known as: internal trigger proxy, organic opens, self-cued sessions
Read it by tenure. Flat from tenure month 1 to month 3 (within 2 points) on a habit route is treated as a Return leak [Analyst]. HK-Q23 (Hooked Ch.2)
Rented engagement. Message sends rising while unprompted share falls for four or more weeks means engagement is being bought with triggers, not formed; expect decay when sends stop.
It needs each session's trigger type, so it is often the first item in a measurement lane. Read it on the habit horizon.
Limits
What we don’t claim
- The Hook Model is a practical design tool, not a validated or complete theory of behavior.Hooked, Introduction
- Habit metrics need the longer habit horizon (weeks to months) before they can be read.
Sources
Hooked · Nir Eyal
Ch.2
Source IDs: HK-Q23
Book content is paraphrased, never quoted at length. Last verified October 24, 2026.
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