Understand ad longevity.
Observation dates are a research signal. Learn what they can and cannot tell you.
Observation span is the elapsed time between the first and last observations in a collected record, rounded down to whole days. It does not establish continuous active delivery. Gaps in collection can occur.
Evergreen: at least 30 days. Hall of fame: at least 90 days. These are research categories, not performance scores. An ad can belong to both.
Dates describe our observations, not necessarily the advertiser’s launch or end dates. Spend, conversions, and profitability cannot be inferred. Always check the last observed date before drawing conclusions.