An observed physical property may be represent a statistical summary with respect to a base property; e.g. maximum UV index over a 3-hour period.<br /></p><p><br /></p><p>The class 'StatisticalQualifier' defines the type of statistical function plus the mechanism that is used to aggregate the base property values to create the statistical summary: length, area, volume, duration or other.<br /></p><p><br /></p><p>Statistical summary properties may be defined by chaining a set of statistical operations together. For example: mean daily maximum temperature over a month period comprises two statistical operations with respect to the base property 'air temperature' - (i) maximum over a 24-hour duration, (ii) mean over a 1-month duration.<br /></p>