Clinical Linearity

Clinical Linearity is a revolutionary concept in the clinical laboratory arena. A new mathematical approach specifically determines whether a data set is linear within a user-defined allowable error. You no longer need to visually judge whether a method is linear.

The algorithm includes the following steps:

• Define allowable error (i.e. CLIA defined PT limits). Allowable error is expressed in units of concentration or percent of concentration.
• Use the allowable error to calculate error bars for each linearity point.
• Attempt to draw a straight line through the error bars. If a straight line can be drawn, then the data are linear within the allowable error.
• Identify and eliminate outliers, continuing until the remaining points are within allowable error or until only three points remain.
• Calculate Intrinsic Error before and after excluding outliers. (Intrinsic Error is the maximum allowable error the system can tolerate and still be linear.)