Interlaboratory Comparison is a quality assurance exercise where multiple laboratories measure the same sample and compare their results — evaluating measurement consistency across different labs, instruments, operators, and methods to identify systematic biases and validate measurement capabilities.

Comparison Types

• Round Robin: The same sample circulates among participating labs — each lab measures and reports results.
• Proficiency Testing (PT): An external organization distributes samples, collects results, and evaluates lab performance.
• Bilateral: Two labs compare results — typically a reference lab and a production lab.
• Key Comparison: BIPM-organized comparisons among national metrology institutes — establishing international equivalence.

Why It Matters

• Consistency: Ensures measurements from different labs are comparable — essential for global manufacturing and supply chains.
• Accreditation: ISO 17025 requires participation in interlaboratory comparisons — mandatory for accredited labs.
• Bias Detection: Identifies labs with systematic biases — enables corrective action before results are compromised.

Interlaboratory Comparison is the measurement cross-check — ensuring different laboratories produce consistent, reliable results through systematic comparison exercises.