5.4.3.37 StandardDeviationSample

The StandardDeviationSample Aggregate defined in Table 85 uses the formula:

where X is each Good raw value in the interval, Avg(X) is the average of the Good raw values, and n is the number of Good raw values in the interval.

For every interval where n = 1, a value of 0 is returned.

If any non-Good values were ignored, the Aggregate quality is uncertain/subnormal.

All interval Aggregates return timestamp of the start of the interval. Unless otherwise indicated, qualities are Good, Calculated.

This calculation is for a sample population where the calculation is done on a subset of the full set of data. Use StandardDeviationPopulation to calculate the standard deviation of a full set of data (see 5.4.3.39). An example would be when the underlying data is sampled from the data source versus stored on an exception basis.