How many readings the window holds before it starts dropping.
Whether the window is still waiting for its first reading.
How many readings the window holds.
The largest reading, or null while the window is empty.
The mean of the readings, or null while the window is empty.
The smallest reading, or null while the window is empty.
Adds a reading, dropping the oldest once the window is full.
The spread between the smallest and largest readings.
The variance of the readings, or null without enough of them.
A rolling window of the most recent readings, with the stats over them.