MD_MeasurementQuality

Dimension

Specifies whether a measurement can be relied on. Possible values: Good, Bad, Uncertain. This table is maintained by hand, since it should basically never change.

Background: OPC (a common HVAC/controls-industry protocol for gathering data from measurement devices and systems) returns values as a triple: Value, quality, timestamp. This table implements the quality (third member) of that triple. Other systems may return equivalents, such as a standard deviation. All these possible values are distilled here down to the three possible values mentioned above.

Although many sub-categories are possible, they are not recorded here, since our purpose is basically to aggregate good data. Additional explanation or text regarding bad or uncertain data should be sought not here, but rather from the originating devices and/or control systems.

Since the values here are text/nominal, and are associated with or applied other (generally numeric) values in fact tables, we need a separate dimension for them.