Understand
Spikes and dips
Each day is a count of stored page views. A day is flagged when it sits outside the band built from the seven days before it.
Daily page views
Counts are stored page views with crawler and headless rows left out. Missing days inside the span are zero.
No stored page views yet.
- No day is outside the band.
The band
For day t, take the previous 7 days, not including t. The mean is their average. The standard deviation divides the sum of squared differences by 6, the sample formula. The band is that mean plus and minus two standard deviations. A count above the band is a spike. A count below it is a dip. The first 7 days have no band.
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