[CLAIM]: Switching our team to a four-day work week will increase productivity, because every company that has tried it has reported productivity gains. [CONTEXT]: Shared by a colleague in a Slack thread during Q4 planning. She read it in a LinkedIn post; no source was linked. 1. **Falsifiable?** Partly. "Will increase productivity" is testable once productivity is defined and measured. "Every company that has tried it has reported gains" is a universal claim — a single counterexample falsifies it. Falsifiable restatement: "In published four-day-week trials, most participating companies reported maintained or improved output per employee, and that result would transfer to our team." 2. **What would need to be true:** - "Productivity" means the same thing in the trials and on our team (output delivered, not hours logged). - Companies that published results represent all companies that tried it — including ones that quietly reverted. - Our team's work pattern resembles the trial participants'. - Gains persist past the novelty period; most trials run months under observation, not years. - Reported gains were measured, not self-assessed. 3. **Evidence for / against.** Supporting: published pilot programs with before/after output metrics; retention and absenteeism data. Refuting: any documented company that reverted after a trial or reported losses; roles with coverage requirements where compressed schedules add cost. 4. **Confounders.** Selection bias — companies that opt in are those best positioned to benefit. Survivorship and publication bias — failed trials rarely become LinkedIn posts, so "every company reported gains" may only mean "every company I heard about." Hawthorne effect. Bundled changes — trials often cut meetings at the same time, so the schedule may not be the active ingredient. 5. **Confidence: 2/5.** The universal "every company" is almost certainly a compression artifact of secondhand sharing, and "others reported gains" does not predict our team's outcome. **Verdict: LIKELY FALSE** as stated — the "every company" version fails on survivorship bias alone; "some companies report gains under trial conditions" may hold but does not predict our team.