Citation Half-Life

Citation Half-Life is the interval over which a source stops appearing in AI-generated answers for a given query set. It matters to agencies because AI visibility fragments faster than classic SERP rankings: a page that held position one for eight months can drop out of ChatGPT answers in weeks when engines reweight toward primary sources. Ahrefs data shows ChatGPT's U.S. citation rankings now favor government health, research, and regulatory sites while explainer-style content has fallen in citation frequency, so agency-produced summaries decay quicker than the primary documents they paraphrase. The practical move is to measure decay per client topic, then set refresh cadence from the measured rate rather than a fixed quarterly retainer cycle. Platforms such as Ayzeo, Pallix, and Voxoria track which domains and sources AI systems cite, giving agencies the raw signal to compute half-life instead of guessing. Treat every citation as a depreciating asset with a known replacement date.