In behavioral analysis, “signal” refers to data that genuinely tells you something meaningful about model performance or user experience, while “noise” is the irrelevant variation that can lead to false conclusions. User feedback data, for instance, is often noisy — a thumbs-down might reflect anything from a genuine model failure to a user who misunderstood the question. Signal-to-noise analysis is the discipline of designing your data collection, filtering, and interpretation practices to surface the meaningful patterns and reduce the influence of noise. For behavior architects, this matters because acting on noise — redesigning behavior based on random variation or unrepresentative complaints — can make things worse. The goal is to identify genuine, reproducible behavioral problems before investing in fixes.