Holidays do not break the count bootstrap, a growth trend does

changepoint-detector on simulated daily counts with known holidays: the block bootstrap cuts false alarms from 85% to 21% on clustered counts.

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changepoint-detectorstatisticstime-series

The --bootstrap penalty in changepoint-detector raises the bar for a changepoint when the noise is clustered. It had been tested alone, with a weekly season and with --trend, but never with --holidays.

Simulated daily counts, 210 days, a holiday every 28th day at 0.3 of the normal rate, 100 series per cell. With a step-free series, false alarms (plain / bootstrap):

clustering of the log rateholidaysholidays + weekly season
none4% / 3%2% / 2%
sd 0.285% / 21%77% / 15%
sd 0.4100% / 65%100% / 67%

Detection of a x1.5 step falls only a few points at sd 0.2 (76% to 72%). So holidays behave like a season, unlike --trend, where the bootstrap barely helped. Limits: synthetic data, holiday dates given exactly, and sd 0.4 is still mostly false alarms. Script and output are in eval/poisson-bootstrap-holidays.*.

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