C

CLIA

Acronym for the Clinical Laboratory Improvements Amendments of 1998 which regulate laboratory practice in the United States.

CLSI

Acronym for the Clinical and Laboratory Standards Institute. Formerly the NCCLS.

consensus group

A group of laboratories submitting data to the Unity™ Interlaboratory Program. Carefully select a consensus group for comparison as statistical outcomes can be quite different based on the nature of the grouping. When choosing a consensus group, always choose the most specific group for which statistics are available.

The available Unity™ Interlaboratory Program consensus groups are:

• Peer (most specific)
  The Peer consensus group is composed of all laboratories using the same instrument, lot number, level, reagent, analytical method, units, and temperature of a test. This is the ideal group for comparison.
• Method (next specific)
  The Method consensus group is composed of all laboratories using the same lot number, level, analytical method, units, and temperature of a test. Use the Method group if there is an insufficient number of laboratories in the Peer group.
• All Labs (least specific)
  The All Labs consensus group is composed of data from all laboratories reporting for the same lot number, level, units, and temperature of a test.

cumulative mean

Also known as floating mean. The mean of all accepted data points entered for a test. If a fixed mean is not defined, the software uses the cumulative (floating) mean for rule evaluation.

CV (coefficient of variation)

The coefficient of variation is the standard deviation expressed as a percentage of the mean. Use the following formula to calculate the CV:

CVR (coefficient of variation ratio)

The coefficient of variation ratio compares a laboratory's precision to that of other laboratories in a consensus group. Use the following formula to calculate the CVR: