Overview
ISO 14802:2012 - Corrosion of metals and alloys: Guidelines for applying statistics to analysis of corrosion data provides guidance on commonly accepted statistical methods useful for interpreting corrosion test results. It is a practical guide rather than a step‑by‑step calculation manual: the standard describes a range of widely accepted statistical approaches used in corrosion testing and highlights how to choose and apply them correctly.
Key topics
- Data scatter and distributions: identification of typical distributions encountered in corrosion work (normal, log‑normal, Poisson, extreme‑value, etc.).
- Visualization: use of histograms and normal probability plots to assess distribution shape.
- Transformations: recommended transforms (e.g., log) to normalize skewed corrosion data and guidance on back‑transforming results.
- Central measures and variability: mean, median, variance, standard deviation, coefficient of variation, range, precision and bias.
- Statistical tests: guidance on hypothesis testing and commonly used tests in corrosion studies (t‑test, F‑test, correlation coefficient, sign test, outside‑count methods).
- Curve fitting and regression: least‑squares linear, polynomial and multiple regression methods for relating variables.
- Analysis of variance (ANOVA): comparing effects and factorial designs used in corrosion experiments.
- Extreme value statistics: treatment of pitting and perforation risks using extreme‑value methods (Gumbel/Weibull approaches) and related probability paper techniques.
- Practical issues: significant digits, propagation of variance, identification of experimental mistakes, and when to use non‑parametric methods.
- Annexes: sample calculations and bibliography for further study.
Applications and users
ISO 14802:2012 is intended for professionals who analyze corrosion test data and need statistically sound interpretation, including:
- corrosion engineers and materials scientists,
- laboratory managers and quality control staff,
- failure analysis and reliability engineers,
- researchers designing corrosion experiments,
- regulatory and standards personnel evaluating test evidence.
Typical uses:
- assessing whether observed differences in corrosion rates are statistically significant,
- fitting time‑to‑failure or pitting depth data (including stress corrosion cracking analyses),
- estimating confidence intervals for corrosion metrics,
- applying extreme value statistics to estimate perforation or pit‑depth probabilities,
- choosing appropriate transformations or non‑parametric tests when distributions are unknown.
Related guidance
ISO 14802:2012 complements other ISO corrosion test standards and procedural documents produced by ISO/TC 156. It is best used alongside specific corrosion test methods and modern data‑reduction/statistical software to produce reliable, reproducible corrosion‑testing conclusions.
Keywords: ISO 14802:2012, corrosion statistics, corrosion testing, normal probability plot, extreme value statistics, regression, ANOVA, pitting, stress corrosion cracking.