TS ISO 5725-4

TS ISO 5725-4 addresses the core problem of estimating how close a standardized measurement method comes to the accepted value, and how much bias is introduced when that method is used in a laboratory. In measurement quality terms, it focuses on trueness rather than precision: trueness concerns systematic deviation from a reference, while precision concerns scatter among repeated results. This distinction is central to interpreting measurement performance correctly.

What the standard covers in practice

The document applies to measurement methods that produce results on a continuous scale and report a single value, even when that value is calculated from multiple observations. It is intended for standardized methods carried out according to the method as specified. In general technical context, this means the method has already been defined well enough that different users can apply it consistently, making bias estimation meaningful and comparable.

Reference values and the limits of applicability

A key condition is that an accepted reference value can be established to stand in for the true value. The standard notes typical ways this may be achieved, such as using a suitable reference material, a suitable measurement standard, a suitable measurement method, or a suitably prepared known sample. It also applies only where bias can be estimated one property at a time; if another property changes the bias through interference or an influencing quantity, this document does not apply. For comparing the trueness of two measurement methods, ISO 5725-6 is the relevant part.

• Provides basic methods for estimating method bias and laboratory bias.
• Offers a practical routine approach for bias estimation.
• Gives brief guidance for personnel designing, performing, or analysing measurements.
• Is limited to standardized methods with continuous-scale, single-value results.
• Does not cover cases where bias depends on another property; comparison of two methods is treated in ISO 5725-6.