RawStandardDeviation Mode

Retrieves the arithmetic standard deviation of raw values for each calculation interval.

Value

Any raw point of bad data quality is ignored.

Quality

If there are no raw samples in the interval or they all have bad quality, then the percent good is 0. Otherwise, percent good is always 100, even if the interval contains bad quality samples.

Example: Calculating the Raw Standard Deviation

The following example demonstrates that only good samples are included in the standard deviation. Perform the following query on the same data set as that in the Count example above:

select timestamp, value, quality from ihrawdata where samplingmode=calculated and calculationmode=rawstandarddeviation and 
timestamp >= '29-Mar-2002 13:30' and timestamp <= '29-Mar-2002 14:30' and tagname = counttag and numberofsamples=1

Time Stamp	Value	Quality
29-Mar-200214:30:00.000	12.73	100.00

Anticipated Usage

The RawStandardDeviation mode is useful for calculating an accurate standard deviation when a sufficient number of raw samples are collected.