Within an acceptable predetermined range. The limits that define the acceptable range may be set using one or more criteria, depending on the intent. A typical analytical “in-control” limit is based on the calculation of the dispersion of the data measured as standard deviation (SD). Subsequent multiplication of the SD by 2 and then by 3 results in what frequently are used as “warning” and “action” limits, respectively. Other statistical or clinical criteria also can be used to set the limits.