The NELAC Institute
The NELAC Institute (TNI) is a 501(c)(3) non-profit organization whose mission is to foster the generation of environmental data of known and documented quality through an open, inclusive, and transparent process that is responsive to the needs of the community. The organization is managed by a Board of Directors and is governed by organizational Bylaws.
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The purpose of this program is to 
develop consensus standards for use by TNI's programs. This group has a support role in assisting other programs with activities such as guidance and standards interpretation.
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One of the ways that TNI 
fosters the generation of data of known and documented quality is through the National Environmental Laboratory Accreditation Program, or NELAP. The purpose of this program is to establish and implement a program for the accreditation of environmental laboratories.
Go to NELAP Home Page...
The purpose of the Proficiency Testing Program 
is to establish and maintain a national PT program to support TNI’s National Environmental Laboratory Accreditation Program, and other activities.
Go to PT Program Home Page...
The purpose of the National Environmental 
Field Activities Program (NEFAP) Executive Committee is to establish and implement an accreditation program for field sampling and measurement organizations (FSMOs).
Go to NEFAP Home Page...
The purpose of the Stationary Source 
Audit Sample Program is to develop consensus standards for the manufacture and analysis of audit samples for source emission testing.
NOTICE: This Program has been suspended effective July 25, 2022. Visit the SSAS Home Page for more information.
Go to SSAS Home Page...
TNI hosts live and on-demand training 
on a variety of topics of interest to the environmental measurement community. TNI also hosts two regularly scheduled meetings per year, typically in January and August. Both are a week long and involve open meetings of TNI committees as well as training courses and other special sessions.
Date Posted: 4-18-2017
TNI has posted a document and a companion spreadsheet to help laboratories calculate Relative Standard Error as required by Section 1.7.1.1 of Module 4 of the TNI Laboratory Accreditation Standard.
How to Calculate RSE (PDF)
RSE Calculation Spreadsheet (Excel)