Measure in three windows. Within two days of the show closing you have target-account meetings held and qualified conversations. At 10 days you have follow-up completion, which is the metric that recovers the most value. At 90 days you have meeting-to-opportunity conversion and influenced pipeline. Closed revenue attributable to the show lands 9 to 18 months later in a project business, so attribute on a rolling basis. Companies that stop attributing at six months routinely undercount their own trade show results by about half.