# Inventory - Evaluation Systems A shelf of lenses. These are organizing concepts rather than measurements: each one decides what a measurement is allowed to mean. Started alongside [[Thesis - Nobody Holds the Whole Map]]; grows as I find more. ## In use | Lens | What it organizes | Where I reach for it | | --- | --- | --- | | **Fitts's law** | Cost of reaching a control, by distance and size | [[UX - Controls Near the Consequence]] | | **Hick's law** | Cost of a choice, by number of options | [[UX - White Space and the Scroll]] | | **Rule of 40** | Whether growth rate and profit margin add up to a healthy product | Judging feature bets against the business they live in | | **Agent roll-up** | Who carries which problem inside a system, and the interfaces where problems leak | [[Pylon Case Study]] · [[Thesis - Agents are for understanding systems; Personas are for understanding people]] | | **Cost per ticket, redefined** | The levers of support cost once deflection and efficiency enter the formula | [[Business Agent Support Cost Formula]] | | **Value stream map** | What becomes of a unit of work, step by step, with the hand-offs exposed | The ticket map I am drawing at work | | **Illusion of explanatory depth** | Why a group believes it understands a system it cannot draw | The reason to map before the meeting | | **Shared mental model · boundary object** | An artifact different roles can point at and argue over | Any diagram meant to survive a room | | **Parkinson's law of triviality · ceremonial activity · sensemaking** | Why talk crowds out mapping | Diagnosing a meeting that produced nothing | | **Now · next · later** | Commitment horizon, with the changelog as the receipts | [[The Responsible Roadmap]] | | **Probes, not monoliths** | Feature scope as an instrument for learning | [[Thesis - Ship Probes, Not Monoliths]] | ## On deck Candidates I have not put to work yet. Each earns a row above only after it organizes a real decision. - **Unit economics (LTV to CAC, payback period)** - whether a feature pays for the attention it costs to acquire - **Goodhart's law** - a measure that becomes a target stops being a measure; the check on every KPI above - **Pareto** - which fifth of the ticket map carries four fifths of the pain - **Metcalfe's law** - value of a networked feature by the square of its participants; relevant to [[Concept - Gift Graph - Consent-Gated Context Between Agents|Gift Graph]] - **Jobs to be Done** - the motivation behind the hire, already noted as an alternate framing in the agents thesis