Analytical goals from biological variation
Derives analytical performance specifications from biological variation.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Within-subject biological variation
- 4.4 CV %
- Between-subject biological variation, for the bias goals
- 12.9 CV %
Result: all three tiers, with the desirable one named first
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Imprecision
- A quarter of the within-subject variation at optimum, a half at desirable, three quarters at minimum.
- Bias
- An eighth, a quarter and three eighths of the square root of the within- and between-subject variations squared and summed.
- Total error
- At each tier: 1.65 times that tier allowable imprecision, plus that tier allowable bias.
- Three tiers
- Not one specification. The biological-variation goal usually quoted is the desirable tier; optimum is twice as hard and minimum is half.
- What they are
- Goals from biology, not from what an analyzer can do. Missing them is not being unusable, and meeting them is not being clinically sufficient.
- Above them
- The Milan hierarchy places outcome-based specifications higher. Where an outcome study exists, it answers the clinical question and this does not.
What you enter
- Within-subject biological variation
- Between-subject biological variation, for the bias goals
How this is calculated
Fraser CG. Biological Variation: From Principles to Practice. Washington: AACC Press; 2001. Sandberg S, Fraser CG, Horvath AR, et al. Defining analytical performance specifications: consensus statement from the 1st Strategic Conference of the EFLM. Clin Chem Lab Med. 2015;53(6):833-835. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.