Statements of Conformity and Decision Rules

Statements of Conformity and Decision Rules

 

Introduction

Statements of conformity and decision rules are two issues that have become a topic of discussion since the revision of the ISO/IEC 17025 standard. The new requirements have become more demanding, assessors are writing deficiencies, and people have a lot of questions about how to comply.

So far, accreditation bodies are providing training on this topic and the ILAC G8 guide has been updated to help labs meet requirements. However, the problem is the training and guides that are currently available are far more advanced than what most laboratories need to meet customer and ISO/IEC 17025 requirements.

In fact, I get questions and complaints on this topic all the time.

Therefore, I created this guide to help you meet requirements in the simplest way possible. You do not need advanced analyses or complex software to evaluate every measurement result.

So, before you spend time and money worrying about it, give this guide read. I am going to teach you how to meet the requirements whether you want to:

  • Provide statements of conformity,
  • Not provide statements of conformity,
  • Take measurement uncertainty into account, or
  • Not take measurement uncertainty into account.

You have options that many people will not tell you about. However, I am going to share with you what I see other labs doing that works.

If you are ready to get started, let’s dive in.

 
 

Statements of Conformity

Before you think about decision rules, you need to first decide how you are going to handle statements of conformity.

In this section, you are going to learn all about statements of conformity;

  1. What is a statement of conformity,
  2. Types of statements of conformity,
  3. Commonly used statements of conformity,
  4. How to determine conformity, and
  5. How to meet ISO/IEC 17025:2017 requirements

 
 

What is Conformity

Before diving into statements of conformity, let’s first define what is conformity.

According to the Oxford Lexico Dictionary, conformity is compliance with standards, rules, or laws.

conformity definition
 
Amongst all the dictionaries and definitions that I read regarding conformity, I liked this definition the best. I believed that it clearly explained how we (laboratories) should define conformity; we determine conformity based on compliance with standards, specifications, and rules.

 
 

What is a Statement of Conformity

A conformity statement or a statement of conformity is an expression that clearly describes the state of compliance or non-compliance to a specification, standard, or requirement.

I found it odd that this term is not defined in the ISO/IEC 17025:2017 or the ILAC G8:09/2019. So, I developed the definition above to give you a description of a statement of conformity.

This topic is not new, but with the revision of the ISO/IEC 17025 it has become popular due to the additional requirements to take risk into account when you provide statements in your test and calibration reports.

So, let’s learn more about statements of conformity.

 
 

Common Examples of Conformity Statements

Below is a list of conformity statements commonly used in test and calibration reports:

  • Pass / Fail
  • In Tolerance / Out of Tolerance
  • In Spec / Out of Spec

 
 

Types of Statements of Conformity

While we are on the topic of statements of conformity, it is important to review the three most common types of conformity used in accredited test and calibration reports.

The three most common types of conformity are:

  1. Compliance
  2. Non-compliance
  3. Indeterminate

 
 

Compliance

statement of conformity compliance pass
 
When the measurement result plus or minus the expanded uncertainty (95% C.L.) does not exceed the specification limit, then compliance with specification can be stated.

 
 

Common Examples of Compliance Statements

Below is a list of commonly used statements of compliance:

  • Compliance
  • Pass
  • In Spec
  • Within Specifications
  • In Tolerance

 
 

Non-Compliance

statement of conformity noncompliance fail
 
When the measurement result plus or minus the expanded uncertainty (95% C.L.) exceeds the specification limit, then non-compliance with specification can be stated.

 
 

Common Examples of Non-Compliance Statements

Below is a list of commonly used statements of non-compliance:

  • Non-Compliance
  • Fail
  • Out of Spec
  • Outside Specifications
  • Out of Tolerance
  • Exceeds Limits

 
 

Indeterminate

statement of conformity indeterminate overlaps does not pass or fail
 
When the measurement result plus or minus the expanded uncertainty (95% C.L.) overlaps the specification limit, it is not possible to state compliance or non-compliance. Therefore, the result is indeterminate.

 
 

Common Examples of Indeterminate Statements
  • Indeterminate
  • Undetermined
  • Unable to Determine Pass/Fail
  • Unable to Determine Compliance/Non-Compliance
  • Not Possible to Determine Compliance/Non-Compliance

 
 

How to Determine Compliance

statement of conformity ilac g8 guide
 
To determine compliance and provide a statement of conformance in your test or calibration reports, follow the steps listed below.

  1. Find your result, expanded uncertainty, and specifications;
  2. Add & Subtract the results and the expanded uncertainty;
  3. Evaluate and determine conformance:
    1. Result ± expanded uncertainty within limits, Pass
    2. Result ± expanded uncertainty exceeds limits, Fail
    3. Result± expanded uncertainty overlaps limits, Indeterminate

 
If you notice, the key is to determine whether the result plus or minus the expanded uncertainty is within, exceeds, or overlaps the limits. By focusing on these three outcomes, you should be able to easily determine which statement of conformity is right for your results.

 
 

Meeting ISO/IEC 17025 Requirements

Statement of conformity is mentioned several times in the 2017 version of the ISO/IEC 17025 standard. Here is a list of the related requirements:

  1. Section 6.2.6b
  2. Section 7.1.3
  3. Section 7.8.3.1b
  4. Section 7.8.4.1e
  5. Section 7.8.6.1

 
 

Section 6.2.6b

ISO/IEC 17025:2017 Requirement

iso 17025 section 6.2.6
 

The laboratory shall authorize personnel to perform specific laboratory activities but not limited to, the following:
b) analysis of results, including statements of conformity or opinions and interpretations;

 

The Key Takeaway

In section 6.2.6b, personnel must be authorized to analyze results including statements of conformity.

 

How to Meet the Requirement

Make sure to authorize personnel to analyze results, including statements of conformity, and include a qualification in their personnel records.

 
 

Section 7.1.3

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.1.3 decision rules
 

When the customer requests a statement of conformity to a specification or standard for the test or calibration, the specification or standard and the decision rule shall be clearly defined. Unless inherent in the requested specification or standard, the decision rule selected shall be communicated to, and agreed with, the customer.

 

The Key Takeaway

In section 7.1.3, when a customer requests statements of conformity, the following information must be clearly defined;

  1. The specification or standard, and
  2. The decision rule.

 

How to Meet the Requirement

If a customer requests a statements of conformity, make sure to clearly define the specification or standard and the decision rules to be used in your quotes, contracts, proposals, etc. You can easily meet this requirement by adding this information in your quotes disclaimer statement, terms and conditions, notes, comments, remarks, etc. Just make sure that it is documented in there.

Otherwise, I have observed other laboratories sending their customers an acknowledgement form that must be signed and returned.

Use the option that works best for your laboratory.

 
 

Section 7.8.3.1b

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.8.3.1b
 

In addition to the requirements listed in 7.8.2, test reports shall, where necessary for the interpretation of the test results, include the following:
b) where relevant, a statement of conformity with requirements or specifications;

 

The Key Takeaway

In section 7.8.3.1, test reports must include a statement of conformity, where:

  • Necessary for the interpretation of results, and
  • Relevant

 

How to Meet the Requirement

If statements of conformity are relevant and necessary for the interpretation of results, make sure to include them in your test reports. If they are not, do not include them.

 
 

Section 7.8.4.1e

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.8.4.1e
 

In addition to the requirements listed in 7.8.2, calibration certificates shall include the following:
e) where relevant, a statement of conformity with requirements or specifications;

 

The Key Takeaway

In section 7.8.4.1, calibration certificates must include a statement of conformity, where relevant.

 

How to Meet the Requirement

If statements of conformity are relevant (to your customer, laboratory, etc.), make sure to include them in your calibration certificates. If they are not, do not include them.

 
 

Section 7.8.6.1

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.8.6.1
 

When a statement of conformity to a specification or standard is provided, the laboratory shall document the decision rule employed, taking into account the level of risk associated with the decision rule employed, and apply the decision rule.

 

The Key Takeaway

In section 7.8.6.1, when a statement of conformity is provided, you must:

  • Document the decision rule used,
  • Take into account the level of risk,
  • Apply the decision rule.

 

How to Meet the Requirement

If you provide statements of conformity in your test or calibration reports, make sure to include the required information in your certificates.

Include your decision rules in the disclaimer, notes, or comments section of your test or calibration certificate.

Take measurement uncertainty (i.e. level of risk) into account when determining conformity.

Make sure to follow the decision rules that you have documented.

 
 

Section 7.8.6.2

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.8.6.2
 

The laboratory shall report on the statement of conformity, such that the statement clearly identifies:
a) to which results the statement of conformity applies;
b) which specifications, standards or parts thereof are met or not;
c) the decision rule applied.

 

The Key Takeaway

In section 7.8.6.2, when a statement of conformity is provided, you must report on the statement to clearly identify;

  • Which results the statement of conformity applies,
  • Which specifications, standards or parts of the specification are met or not met,
  • The decision rule applied.

 

How to Meet the Requirement

If you provide statements of conformity in your reports, make sure your conformity statements clearly show which results they apply to. Typically, this is not a problem for most labs because statements of conformity (e.g. Pass or Fail) are usually reported alongside each result.

Additionally, make sure to provide information on the specifications or standard in your certificates. Again, this is typically not a problem since most labs report specifications or limits with their measurement results.

Finally, make sure that your decision rules are provided in your test or calibration certificates. These can be included in the disclaimer, notes, or comments section of your test or calibration certificates.

In the next section, you are going to learn everything that you need to know about decision rules.

 
 

Decision Rules

Decision rules is the new requirement of the ISO/IEC 17025 standard that has a lot of people confused. Don’t let it intimidate you!

You simply need to describe how you decide whether a result passes, fails, or is indeterminate.

In this section, you will learn:

  1. What are decision rules,
  2. How to meet ISO/IEC 17025 requirements,
  3. What options you have with decision rules, and
  4. Examples of decision rules in use.

 
 

What are Decision Rules

iso 17025 section 3.7 decision rule definition
 
According to ISO/IEC 17025:2017, section 3.7, a decision rule is a rule that describes how measurement uncertainty is accounted for when stating conformity with a specified requirement.

As you can see, the definition is very clear. What are your rules for taking measurement uncertainty into account when providing statements of conformity. How you determine whether a result passes, fails, or is indeterminate.

 
 

Meeting ISO/IEC 17025 Requirements

Section 7.8.6.1

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.8.6
 

The Key Takeaway

According to section 7.8.6.1 of the ISO/IEC 17025 standard, when a statement of conformity is provided, the laboratory shall:

  1. Document the decision rule used,
  2. Take into account the level of risk, and
  3. Apply the decision rule.

 

How to Meet the Requirement

To meet this requirement, you need to simply document a set of rules that describes how you:

  • take measurement uncertainty into account when determining conformity, and
  • decide whether a result Passes, Fails, or is Indeterminate

Then, apply those rules when providing statements of conformity. The key here is “when providing statements of conformity.” If you do not provide statements of conformity, then you do not need to include this information in your reports.

In the next section, you will see how other accredited laboratories are using decision rules and statements of conformity.

 
 

Decision Rule Options

When documenting, applying, and reporting decision rules, you have a few options. The three options listed below are actual real-world applications used by laboratories accredited to the latest version of the standard.

Most accredited laboratories use one of the following three options:

  1. Take uncertainty into account when making conformity statements,
  2. Do not take uncertainty into account when making conformity statements, or
  3. Do not make conformity statements.

 
 

Decision Rule Examples

Now that you have been given options to document and apply decision rules, let’s look at some real-world examples of each option in use.

In this section, you will see three decision rule examples;

  1. Taking uncertainty into account,
  2. Not taking uncertainty into account, and
  3. Not providing statements of conformity.

 
 

Example 1: Taking Uncertainty into Account

In this example, you will see how Keysight Technologies documents and applies decision rules and provides statements of conformity in their calibration certificates. Keysight does a great job meeting the ISO/IEC 17025:2017 requirements and implementing a process that I believe was intended by the standard.

Each Keysight calibration report provides a section that gives a list of the statements of conformity used in their reports and describes their decision rules when making these statements.

If you are looking to meet requirements and implement a similar process, this is an example that you will want to see.

Look at the exert from a Keysight calibration report to see how to they document and apply decision rules and statements of conformity.

keysight technologies decision rules

 

How to Implement These Decision Rules in Your Laboratory

If you want to implement something similar, look at the statement below. You can simply copy and paste this in your test or calibration reports to help you meet the new ISO/IEC 17025 requirements.

“Where statements of conformity are made in this report, the following decision rules are applied:

  1. PASS – Results ± expanded uncertainty within limits/specifications
  2. PASS‡ – Results are within limits/specifications but overlap when expanded uncertainty is taken into account
  3. FAIL‡ – Results exceed limits/specifications but overlap when expanded uncertainty is taken into account
  4. FAIL – Results ± expanded uncertainty exceeds limits/specifications”

 
 

Example 2: Not Taking Uncertainty into Account

In this example, you will see how Epsilon provides statements of conformity without taking measurement uncertainty into account.

In the image below, you will see that their calibration reports state:

It is the responsibility of the end user to determine if it is appropriate for your specific application.

 
epsilon decision rules
 
So, Epsilon states “PASS” in their calibration reports but does not take measurement uncertainty into account when making this statement of conformity.

This practice is not favored by many assessors, but you can use it if you document your decision rules properly and communicate this to your customers as part of contract review. If you include this information in your quotes and customers still decide to do business with you (e.g. issue a purchase order, sign a contract, etc.), they are accepting this practice.

Additionally, you will want to make sure that your customers are not complaining that you are not taking measurement uncertainty into account. If they are complaining, you may still receive a deficiency during an assessment.

 

How to Implement These Decision Rules in Your Laboratory

If you plan to provide statements of conformity without taking measurement uncertainty into account, then you may want to add a statement to your test or calibration reports that is similar to the statement below;

“Statements of conformity (e.g. Pass/Fail) to specifications are made in this report without taking measurement uncertainty into account except when requested by the customer. Where statements of conformity are made in this report, the following decision rules are applied:

  1. PASS – Results within limits/specifications
  2. FAIL – Results exceed limits/specifications”

 
 

Example 3: Do Not Report Statements of Conformity

In this example, you will see how Fluke Calibration does not provide statements of conformity. Instead they use symbols to indicate that a result may need to be reviewed further.

In the image below, you will see that Fluke calibration certificates state:

No statement of compliance with specifications is made or implied on this certificate. However, measurement results are reviewed, where applicable, to establish where any measurement result exceeded the manufacturer’s specifications. Measurement results greater than limits of error are indicated by ’!’.

 
fluke calibration decision rules
 
This practice is used by other laboratories. However, in some cases, it has been interpreted by several assessors as a statement of conformity. If you want to use a similar process, make sure to be careful. You may still receive a deficiency.

At the time this guide was published, Fluke Calibration was still accredited to the 2005 version of the standard. I am curious to see what new processes they will implement when converting to the 2017 version of the standard.

Keep an eye on their reports this year. Their A2LA accreditation certificate (2166.01) expires on 04/30/2020 10/31/2020 (looks like a 6-month extension was applied on 01/9/2020).

 

How to Implement These Decision Rules in Your Laboratory

If you do not want to provide statements of conformity in your test or calibration reports, consider adding the statement below to your certificates. Remember to not provide any information in your reports that may be considered a statement of conformity.

“Statements of conformity to specifications are not made or implied in this report. Review the results, expanded uncertainty, and specifications to ensure they meet your requirements.”

 
 

Communicating Decision Rules Your Customer

Finally, make sure that you communicate your decision rules to your customers.

 

ISO/IEC 17025:2017 Requirement

iso 17025 section 7.1.3 decision rules
 
Section 7.1.3 of the ISO/IEC 17025:2017 standard states:

When the customer requests a statement of conformity to a specification or standard for the test or calibration, the specification or standard and the decision rule shall be clearly defined. Unless inherent in the requested specification of standard, the decision rule selected shall be communicated to, and agreed with, the customer.

 

How to Implement These Decision Rules in Your Laboratory

You need to incorporate this into your contract review process; or else, you will not meet ISO/IEC 17025 requirements.

Therefore, it is very important that you include a note or disclaimer in your quotes, proposals, contracts, etc. to clearly communicate your decision rules to your customers.

If they provide you with a purchase order or payment in reference to one of your quotes, they are effectively agreeing to your decision rules. This is the easiest way (in my opinion) to meet this requirement.

However, you should be aware that this is not a fool-proof process of communicating decision rules to your customers. You need to make sure that your customers are not complaining about your decision rules or statements of conformity (or lack of).

If you have customers that complain about your decision rules after services are rendered, you may have a problem that could result in a deficiency during an assessment. I have observed this when reviewing audit results. So, assessors may check your complaint log if they do not like your process.

However, consider the bright side of this. If an assessor does not like your process of communicating decision rules using a disclaimer in your quote and you have no complaints, then consider using your complaint log as objective evidence that your customers have agreed to your decision rules.

 

“Important: Make sure to communicate decision rules to your customers using a note or disclaimer your quotes, proposals, contracts, etc.”

 
 

Conclusion

Statements of conformity and decision rules are two topics of the new revision of the ISO/IEC 17025 standard that have caused problems for a lot of laboratories who are seeking solutions to meet requirements. Even though there are guides and training available, most of them provide solutions that are too advanced for what most laboratories (and their customers) need.

In this guide, you should have learned all about statements of conformity and decision rules; and, some simple solutions to help you meet requirements.

Review some of options and examples given to you in this guide and decide which option will work best for your laboratory. Next, update your quality management system, quotes, and certificates. Finally, implement the process that you have chosen and monitor your results to see if it is effective for your laboratory and customers.

If it is effective, congratulations! If it is not effective, revise your process until it is effective.

What option do you use?

Leave a comment below and let me know.

About the Author

Richard Hogan

Richard Hogan is the CEO of ISO Budgets, L.L.C., a U.S.-based consulting and data analysis firm. Services include measurement consulting, data analysis, uncertainty budgets, and control charts. Richard is a systems engineer who has laboratory management and quality control experience in the Metrology industry. He specializes in uncertainty analysis, industrial statistics, and process optimization. Richard holds a Masters degree in Engineering from Old Dominion University in Norfolk, VA. Connect with Richard on LinkedIn.

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