From AMS Glossary
- The previous value in a time series.
Thus, if x(t) denotes the present value, the value of persistence would be x(t - 1), whence the latter value is regarded as "persisting." It is used as an objective standard in the verification of weather forecasts. Sometimes it is extended to mean x(t - h) where h is arbitrary.
- (Also called inertial forecast.) In general, the tendency for the occurrence of a specific event to be more probable, at a given time, if that same event has occurred in the immediately preceding time period.