Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Statistical Evaluation of a Round-Robin Experiment: Uncertainies in Ferrite Measurement in Weldments



Thomas A. Siewert, J C. Farrar, Z Zhang


A Round Robin was organized to measure ferrite (FN) levels in the weld metal of five stainless steel weldments, including: types AISI 308H (with controlled ferrite), 2205 (22% Cr duplex), 309 Mo, 16-8-2 (316H - a lean composition with controlled ferrite), and 316NF (with negligible ferrite). Each weldment was sliced into several pieces, and various locations on the surfaces of these pieces were specified for measurements. In addition, some locations on the weld caps andweld roots were given different finishes as-welded, lightly polished, ground flush and filed flush) to assess the effect of these surface finishes on the measurements. The specimens were circulated to 17 different laboratories in 9 different countries around the world. A Summary Report (distributed to two Commissions within the International Institute of Welding in 2001, asIIW Documents 11-1440-01 and IXH-512-01) presented the data and some preliminary analysis of the data. That report recommended a more comprehensive statistical analysis, which is the subject of this report.
International Institute of Welding


Box and whiskers plots, ferrite, FN, round robin, statistical analysis, weldments, welds


Siewert, T. , Farrar, J. and Zhang, Z. (2002), Statistical Evaluation of a Round-Robin Experiment: Uncertainies in Ferrite Measurement in Weldments, International Institute of Welding (Accessed May 20, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created July 1, 2002, Updated February 19, 2017