lifesight-experiment-designlisted

# Lifesight Experiment Design Incrementality is the ground truth of the whole platform — the difference between "this channel got credit" and "this channel *caused* growth." This spoke does two jobs: **design** a test that will answer a causal question, and **read** the results of one that ran. It's also where you recommend *what's worth testing* — usually the biggest, most expensive assumption the user is about to act on. **Prerequisites (router handles):** workspace calibrated, profile loaded. Operate under `lifesight-core`; present under `lifesight-rendering`. Load both. ## Designing a test 1. **Pin the causal question.** What decision hangs on it? "Is Linear TV worth its spend?" "Will scaling TikTok actually add revenue or just shift it?" A test with no decision attached is wasted budget. 2. **Pick the design** (via `ask_mia`'s experiment workflow): - **Geo holdout** — withhold a channel in matched control markets to measure the lift it's currently driving. The default for "is this incremental?" - **Geo scale-up** — increase spend in treatment markets to probe further up the response curve. For "should I spend more here?" - **Time / segment** designs where geo isn't feasible. 3. **Sanity-check feasibility before launching:** is there enough spend/volume and enough matched markets to detect a realistic effect? Name the **minimum detectable lift** and the test duration up front — an underpowered test wastes weeks and answers nothing. #