Nanotechnology · evidence and evaluation

Report a nanomaterial size the way a measurement is reported

A single number is not a size. Report the measurand, the method, the distribution and an uncertainty with its basis, or the result cannot be compared with anyone else’s.

How it works

NIST TN 1297 classifies uncertainty components by how they are evaluated — Type A from statistical analysis of repeated observations, Type B by other means, such as instrument specifications or prior data — and expects a reported result to carry that basis. Applied to nanomaterials, that means a stated diameter should say what was measured (a projected area diameter from images, a hydrodynamic diameter from scattering), over how many objects or runs, and with what contributions to the stated spread. Distribution width is not uncertainty: a wide, well-measured distribution is a property of the sample, while uncertainty describes how well the measurement pinned it down. Both belong in the record, separately.

A concrete case

Two reports state “32 nm”. One is a mean over 500 imaged particles with the standard deviation of the population and a stated magnification calibration; the other is a single scattering run’s intensity-weighted mean. Only the first supports a comparison with a specification written on a number-weighted basis.

What this establishes

That the reporting structure for a nanomaterial measurement is the ordinary metrological one, and that its components have defined meanings.

What it does not

No uncertainty budget for any instrument or material is supplied here, and nothing on this page calibrates or certifies a measurement.

Questions worth asking

  • Separate the width of the population from the uncertainty of the estimate; ask for both.
  • Ask which uncertainty components were evaluated statistically and which came from specifications.
  • Ask how the calibration of the instrument was established and when.

Sources

  • NIST Technical Note 1297 — Guidelines for Evaluating and Expressing Uncertainty ↗

    Uncertainty components are classified by how they are evaluated — Type A by statistical analysis of repeated observations, Type B by other means — and a reported result is expected to carry the basis of its uncertainty rather than a bare number.

    Boundary: A general metrology guideline. It supplies no particle-size uncertainty budget and certifies no instrument or laboratory.

    Locator, anchor and reuse basis

    Read at: §2 Classification of components of uncertainty; §3 Type A; §4 Type B; §7 Reporting uncertainty. Inspected 2026-09-19. Original paraphrase and link only.

    Verify by searching the source for: the statistical analysis of series of observations is termed a Type A evaluation. If that phrase is not there, or does not carry the meaning stated above, this citation is wrong and we want to know.

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Maha Strategies publishes explanation and evaluation method. We make no nanomaterials, run no characterisation, certify nothing, and give no medical or legal advice.