Transcript Slide 1

AIHA-LAP, LLC Webinar
Measurement Uncertainty and
Traceability Policies Review
Friday, April 30, 2010
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Webinar Outline
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Introduction of Presenters/Moderators
Ground Rules
Background
What’s New
Basis of the new Policies
Policy Review - Section by Section
Discussion of guidance and examples
What to Expect Beginning April 1
Questions and Answers
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Webinar Speakers
• Speakers:
– Margie Breida
– Ronald Peters (MU)
– Maureen Hamilton (Traceability)
• Moderator:
– Sage Morgante
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Ground Rules
• All phone lines will be muted during the
presentation.
• Speakers will present information in the slides.
• Questions can be be typed in the chat box
during the presentation. Participants should
type in their name/laboratory and a question.
• When the speaker thinks it is appropriate to take
questions, he/she will pause and the moderator
will read the questions.
• We will answer as many questions as we can,
but not all questions will be answered.
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Ground Rules (cont’d)
• If you experience technical problems or you
cannot connect to the call, please contact us at
(703) 846-0739.
5
Background
• AIHA-LAP, LLC evaluation for
international recognition (APLAC/IAAC)
– MU and traceability changes needed so that
we are more aligned with other accreditation
bodies
• New policies, guidance and examples
replace previous guidance.
• New MU and traceability documents
posted on web site on February 18, 2010.
• Became effective April 1, 2010.
• All assessments are now being
conducted against these new policies.
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What’s New?
• Follow links to the 2010 AIHA-LAP, LLC
Policy Modules
• Appendix G
– Policy on the Estimation of Uncertainty
of Measurement (Rev. 0, effect. April 1, 2010)
• Guidance on the Estimation of Uncertainty
of Measurement (Rev. 1, 2/17/10)
• Guidance on Statistical Analysis of EMLAP
QC (Rev. 1, 2/17/10)
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What’s New?
• Appendix H
– Policy on Traceability of Measurement
(Rev. 0, effect. April 1, 2010)
• Guidance on Traceability of Measurement
(Rev. 1, 2/17/10)
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What’s New?
• Example Excel Workbooks:
– CALA Example Internal Calibration Workbook
– Example Chemistry Measurement Uncertainty
Calculations
– Example Microbiology Measurement
Uncertainty Calculations
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Important to Remember!
• Policy Documents – Include
Requirements
• Guidance Documents – Include
guidance and recommendations –
These are NOT Requirements but
include acceptable approaches
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Policy on the Estimation of
Uncertainty of Measurement
(MU Policy)
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1. Scope
2. References
3. Terms and Definitions
4. Background
5. AIHA-LAP, LLC Uncertainty Policy
6. Assessment for Accreditation
7. Guidance and Examples
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Basis of MU Policy/Guidance
References
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ISO/IEC 17025:2005 - General Requirements for the Competence of Testing and
Calibration Laboratories
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Guide to the Uncertainty of Measurement (GUM) published by ISO, IEC,
CIPM, BIPM, Eurachem, etc
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Quantifying Uncertainty in Analytical Measurement, 2nd Edition, 2000,
Eurachem/CITAC
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APLAC TC 005 (2006) Interpretation and Guidance on the Estimation of
Uncertainty of Measurement in Testing, Asia-Pacific Laboratory Cooperation
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ILAC Guide 17: Introducing the Concept of Uncertainty of Measurement in
Testing in Association with the Application of the Standard ISO/IEC 17025. 2002,
ILAC: Rhodes, NSW, Australia.
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CALA P19 – CALA Policy on the Estimation of Uncertainty of Measurement in
Environmental Testing.
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Basis of MU Policy
REQUIREMENTS
• ISO/IEC 17025 Section 5.4.6.2 “Testing
laboratories shall have and shall apply
procedures for estimating uncertainty of
measurement.”
• ISO/IEC 17025 Section 5.4.6.3 “When
estimating the uncertainty of measurement, all
uncertainty components which are of importance
in the given situation shall be taken into account
using appropriate methods of analysis.”
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Basis of MU Policy/Guidance
Key Terms and Definitions
• uncertainty of measurement (VIM 2.26 JCGM 200:2008):
non-negative parameter characterizing the dispersion of
the quantity values being attributed to a measurand, based
on the information used
• NOTE 1 Measurement uncertainty includes components
arising from systematic effects, such as components
associated with corrections and the assigned quantity
values of measurement standards, as well as the
definitional uncertainty. Sometimes estimated systematic
effects are not corrected for but, instead, associated
measurement uncertainty components are incorporated.
• NOTE 2 The parameter may be, for example, a standard
deviation called standard measurement uncertainty (or a
specified multiple of it), or the half-width of an interval
having a stated coverage probability.
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Basis of MU Policy/Guidance
Key Terms and Definitions
•
uncertainty of measurement (VIM 2.26 JCGM 200:2008):
•
NOTE 3 Measurement uncertainty comprises, in general, many
components. Some of these may be evaluated by Type A
evaluation of measurement uncertainty from the statistical
distribution of the quantity values from series of measurements
and can be characterized by standard deviations. The other
components, which may be evaluated by Type B evaluation of
measurement uncertainty, can also be characterized by standard
deviations, evaluated from probability density functions based on
experience or other information.
•
NOTE 4 In general, for a given set of information, it is understood
that the measurement uncertainty is associated with a stated
quantity value attributed to the measurand. A modification of this
value results in a modification of the associated uncertainty.
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Basis of MU Policy
REQUIREMENTS
• ISO/IEC 17025 Section 5.10.3.1 “In addition to
the requirements listed in 5.10.2, test reports
shall, where necessary for the interpretation of
the test results, include the following:
c) where applicable, a statement on the
estimated uncertainty of measurement;
information on uncertainty is needed in test
reports when it is relevant to the validity or
application of the test results, when a
customer's instruction so requires, or when
the uncertainty affects compliance to a
specification limit;”
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5.0 AIHA-LAP, LLC Uncertainty Policy
• The requirement which underlies this policy is
given in ISO/IEC 17025, Clauses 5.4.6 and
5.10.3.1 c).
• Laboratories accredited under the AIHA-LAP, LLC
Accreditation Program shall fulfil the following
requirements with respect to the estimation of
uncertainty of measurement for tests associated
with their scope of accreditation:
17
AIHA-LAP, LLC Uncertainty Policy
• 5.1 Laboratories shall be able to demonstrate their
ability to estimate measurement uncertainty for all
accredited quantitative test methods. In those
cases where a rigorous estimation is not possible,
the laboratory must make a reasonable attempt to
estimate the uncertainty of test results. All
approaches that provide a reasonable and valid
estimation of uncertainty are equally acceptable.
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AIHA-LAP, LLC Uncertainty Policy
• 5.2 Laboratories shall make independent
estimations of uncertainty for tests performed on
samples with significantly different matrices. For
example, estimations made for filter samples
cannot be applied to bulk samples.
• 5.3 Estimations of measurement uncertainty are
not needed where the reported test results are
qualitative. Laboratories are, however, expected to
have an understanding of the contributors to
variability of test results. Examples of such tests
are those that report only organism identifications
or presence/absence.
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AIHA-LAP, LLC Uncertainty Policy
• 5.4 Laboratories shall have a written procedure
describing the process used to estimate
measurement uncertainty, including at a minimum:
– 5.4.1
Definition of the measurand.
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Basis of MU Policy/Guidance
Key Terms and Definitions
• measurand (VIM 2.3 JCGM 200:2008): quantity
intended to be measured
• NOTE The specification of a measurand requires
knowledge of the kind of quantity, description of
the state of the phenomenon, body, or substance
carrying the quantity, including any relevant
component, and the chemical entities involved.
• NOTE In chemistry, “analyte”, or the name of a
substance or compound, are terms sometimes
used for ‘measurand’. This usage is erroneous
because these terms do not refer to quantities
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AIHA-LAP, LLC Uncertainty Policy
• 5.4 Laboratories shall have a written procedure
describing the process used to estimate
measurement uncertainty, including at a minimum:
– 5.4.1 Definition of the measurand.
– 5.4.2 Identification of the contributors to
uncertainly.
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MU Guidance Document
Consider the following categories or processes as
listed by CALA and ILAC Guide 17:
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Sampling or sub-sampling – in-house sub-sampling typically applies
only to bulk samples tested in AIHA-LAP, LLC laboratories. Note
that field sampling is most often outside the responsibilities of the
laboratory. In such cases, the laboratory should clearly state
that any estimates of uncertainty reported with samples relate
only to analytical uncertainty.
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Transportation, storage and handling of samples
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Preparation of samples -all steps of the sample procedure prior to
analysis. This can include variations in drying, grinding, filtering,
weighings, dispensing of materials, extractant backgrounds, etc.
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MU Guidance Document
Consider the following categories or processes as
listed by CALA and ILAC Guide 17:
•
Environmental and measurement conditions - those conditions that
can impact some test results (e.g., gravimetry, microbiology) when
they vary (e.g., temperature or humidity of the balance room,
seasonal changes in microbiological background of micro labs,
etc.).
•
The personnel carrying out the tests -This is especially important
with subjective tests such as microscopy and organism
identification.
•
Variations in the test procedure - for example, different recoveries
for different batches of media, impurities in reagent lots, the effect of
different extraction, digestion or incubation times and temperatures,
percentages of microscopic samples read, etc.
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AIHA-LAP, LLC Uncertainty Policy
Consider the following categories or processes as
listed by CALA and ILAC Guide 17:
•
The measuring instruments - variations in baseline drift, day to day
calibration differences, carry over effects, interferences specific to
the test method, microscope magnification used, etc.
•
Calibration standards or reference materials - uncertainty related to
reference materials or due to preparation differences, etc.
Uncertainty estimates may come from certificates of analysis or
estimations based on provider claims.
•
Methods of generating test results - uncertainty due to data
interpretation (e.g., peak integration, baseline manipulation, etc.),
blank corrections, differences in how the software was used, other
data manipulations, etc.
•
Corrections for systematic effects - if test results are corrected for
bias, include the uncertainty of the correction.
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AIHA-LAP, LLC Uncertainty Policy
• 5.4 Laboratories shall have a written procedure
describing the process used to estimate
measurement uncertainty, including at a minimum:
– 5.4.1 Definition of the measurand.
– 5.4.2 Identification of the contributors to
uncertainly.
– 5.4.3 Details of the approaches used for
estimating measurement uncertainty, such as
Type A and/or Type B.
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Basis of MU Policy/Guidance
Key Terms and Definitions
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type A evaluation of measurement uncertainty (VIM 2.28 JCGM 200:2008):
evaluation of a component of measurement uncertainty by a statistical analysis of
measured quantity values obtained under defined measurement conditions
NOTE 1 For various types of measurement conditions, see repeatability condition
of measurement, intermediate precision condition of measurement, and
reproducibility condition of measurement.
type B evaluation of measurement uncertainty (VIM 2.29 JCGM 200:2008):
evaluation of a component of measurement uncertainty determined by means other
than a Type A evaluation of measurement uncertainty
EXAMPLES Evaluation based on information
— associated with authoritative published quantity values,
— associated with the quantity value of a certified reference material,
— obtained from a calibration certificate,
— about drift,
— obtained from the accuracy class of a verified measuring instrument,
obtained from limits deduced through personal experience.
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AIHA-LAP, LLC Uncertainty Policy
When using the Type A approach, laboratories shall
utilize one or more of the following options. These
options are generally considered from 1) most
suitable, to 4) least suitable:
• 1) Uncertainty specified within a standard method.
In those cases where a well-recognized test
method (such as a peer-reviewed AOAC, NIOSH,
OSHA, ASTM, etc. method), specifies limits to the
values of the major sources of uncertainty of
measurement and specifies the form of
presentation of calculated results, laboratories
need not do anything more than follow the
reporting instructions as long as they can
demonstrate they follow the reference method
without modification and can meet the specified
reliability.
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AIHA-LAP, LLC Uncertainty Policy
• 2) Laboratory Control Samples (LCS) and Matrix
Spikes. In cases where matrix specific LCS (CRM
or media spikes) and/or matrix spike data are
available, include uncertainty estimated from the
standard deviation of long term data collected from
routine sample runs for existing test methods or
from the standard deviation of the LCS or matrix
spike data for method validation/verification
studies for new test methods.
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AIHA-LAP, LLC Uncertainty Policy
•
3) Duplicate Data. In cases where sub-sampling
occurs and there are data over the reporting limit,
include uncertainty estimated from long term
duplicate data collected from routine sample runs
for existing test methods or method
validation/verification studies for new test
methods.
•
4) Proficiency Testing (PT) Sample Data. In cases
where the previous options are not available and
where PT samples are analyzed with sufficient
data above the reporting limit, pooled PT sample
data can be used to estimate uncertainty.
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AIHA-LAP, LLC Uncertainty Policy
5.4 Laboratories shall have a written procedure
describing the process used to estimate
measurement uncertainty, including at a
minimum:
•
5.4.4 Identification of the contributors of variability
for qualitative test methods.
•
5.4.5 All calculations used to estimate
measurement uncertainty and bias.
•
5.4.6 The reporting procedure.
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AIHA-LAP, LLC Uncertainty Policy
•
5.5 Laboratories are required to re-estimate
measurement uncertainty when changes to their
operations are made that may affect sources of
uncertainty.
•
5.6 Laboratories shall report the expanded
measurement uncertainty, along with the reported
analyte concentration, in the same units as analyte
concentration, when:
– • it is relevant to the validity or application of the
test results, or
– • a customer's instructions so requires, or
– • the uncertainty affects compliance to a
specification limit.
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AIHA-LAP, LLC Uncertainty Policy
•
5.7 When reporting measurement uncertainty, the
test report shall include the coverage factor and
confidence level used in the estimations (typically
k = approximately 2 at the 95% confidence level).
•
5.8 When the test method has a known and
uncorrected systematic bias, it shall be reported
separately from the test result and uncertainty
estimation, as a probable bias value
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Basis of MU Policy/Guidance
Key Terms and Definitions
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•
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•
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Expanded uncertainty (VIM 2.35 JCGM 200:2008): product of a
combined standard measurement uncertainty and a factor
larger than the number one
NOTE 1 The factor depends upon the type of probability
distribution of the output quantity in a measurement model and
on the selected coverage probability.
NOTE 2 The term “factor” in this definition refers to a coverage
factor.
NOTE 3 Expanded measurement uncertainty is termed “overall
uncertainty” in paragraph 5 of Recommendation INC-1 (1980)
(see the GUM) and simply “uncertainty” in IEC documents.
combined standard uncertainty (VIM 2.31 JCGM 200:2008):
standard measurement uncertainty that is obtained using the
individual standard measurement uncertainties associated
with the input quantities in a measurement model
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Basis of MU Policy/Guidance
Key Terms and Definitions
• coverage factor (VIM 2.38 JCGM 200:2008): number
larger than one by which a combined standard
measurement uncertainty is multiplied to obtain an
expanded measurement uncertainty
• NOTE: A coverage factor, k, is typically in the range of 2 to
3.
• standard uncertainty (VIM 2.30 JCGM 200:2008):
measurement uncertainty expressed as a standard
deviation
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Summary of Guidance Document
Steps
• Review and identify the contributors
• Determine if contributors are
accounted for with existing QC data
• Compile the applicable QC data and
any other contributors and perform
calculation of combined uncertainty
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Summary of Guidance Document
Steps
• Combined uncertainty
SDc = √ [ SD12 + SD22 + … + SDn2 ]
It may be beneficial to use RSD instead of
SD as it allows for the concentration
dependence of SD.
NOTE: Sources that have an SD of less
than 1/3 of the largest SD can be
eliminated
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Summary of Guidance Document
Steps
•
Calculate the expanded uncertainty
– Apply the appropriate coverage factor 'k'. Calculate the
expanded uncertainty by multiplying the combined
standard uncertainty by the appropriate coverage factor
(k) to give an expanded uncertainty with the desired
confidence level. The factor k is the confidence interval
Student distribution t-factor for n-1 degrees of freedom.
For a confidence level of 95%, k is approximately 2 for a
data set of 30 points or more, for normally distributed
data sets.
– Expanded measurement uncertainty = k x SDc
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Summary of Guidance Document
Steps
•
Reporting test results with the expanded
measurement uncertainty
– Total benzene concentration of 88 ug/sample + 11
ug/sample at the 95% confidence level (k=2).
•
Where bias is present, report it along with the
uncertainty as a probable bias in a manner such
as the following example:
– Total lead concentration of 78 ug/sample + 12 ug/filter at
the 95% confidence level (k=2). This method has an
average recovery of 94%, or at this level, a probable bias
of -5 ug/filter.
•
Alternate forms of reporting uncertainty and bias
are acceptable as long as required information is
clearly presented.
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6. ASSESSMENT FOR
ACCREDITATION
•
During assessment and surveillance of a
laboratory, the assessor will evaluate the
capability of the laboratory to estimate the
measurement uncertainty for test methods
included in the laboratory’s scope of accreditation.
The assessor will verify that the methods of
estimation applied are valid, all significant
contributors to uncertainty have been considered,
and all the criteria of the AIHA-LAP, LLC policy
are met.
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Guidance and Examples
• Refer to the AIHA-LAP, LLC
Guidance on the Estimation of
Uncertainty of Measurement for
suggestions and examples for
implementing the policies and
helpful references.
• Example Excel spreadsheets also
on the website
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Guidance and Examples
“Example Chemistry Measurement
Uncertainty Calculations” workbook
includes:
• Common Contributors to Measurement
Uncertainty
• Example contributors and calculations
for Chromatography
• Example contributors and calculations
for Lead in Paint
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Guidance and Examples
“Example Microbiology Measurement
Uncertainty Calculations” workbook
includes:
• Example contributors and
calculations for Direct Examination
Air
• Example contributors and
calculations for culturable analyses
(fungal swabs)
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Summary of Requirements
• Section 5.1 requires laboratories to be able to
calculate an estimated measurement
uncertainty, when requested, for all quantitative
test methods covered by their AIHA LAP, LLC
accreditation.
• Section 5.2 requires laboratories to treat each
significantly different matrix (e.g., filters vs.
bulks) separately when estimating
measurement uncertainty.
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Summary of Requirements
• Section 5.3 addresses qualitative test methods.
For these methods, laboratories are only
required to understand the contributors to
variability of test results and attempt to
minimize them.
45
Summary of Requirements
• Section 5.4 requires laboratories to have a
written procedure describing how they estimate
measurement uncertainty.
Procedures must define the measurand, identify
contributors to uncertainty, detail the approach
that will be used to make the measurement
uncertainty estimation, identify the calculations
to be used to estimate measurement
uncertainty and bias, and define how the
information will be reported when required.
Types of QC data that may be used in making
the estimates are identified.
46
Summary of Requirements
• Section 5.5 identifies conditions that will
require laboratories to re-estimate
measurement uncertainty of a test method.
• Section 5.6 defines when and how
measurement uncertainty, as expanded
measurement uncertainty, shall be reported.
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Summary of Requirements
• Section 5.7 requires the coverage factor used
and confidence level to be included when
reporting measurement uncertainty.
• Section 5.8 identifies requirements for
reporting bias when it is known and a correction
for it has not been applied to the reported
result.
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Beginning April 1, 2010
• Your procedures must include all elements in
Section 5 of the AIHA-LAP,LLC measurement
uncertainty policy.
• The procedures must be implemented.
• All contributors to MU must be considered and
dealt with in a defensible manner.
• The calculations must make sense.
• Your lab must have the ability to report MU,
even if the customer is currently not requesting
it.
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Questions?
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Traceability Documents
• Appendix H
– Policy on Traceability
of Measurement (Rev. 0, effect. April 1, 2010)
• Guidance on Traceability of Measurement
(Rev. 1, 2/17/10)
• CALA Example Internal Calibration
Workbook
51
Policy on the Traceability of
Measurement
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(Traceability Policy)
1. Scope
2. References
3. Terms and Definitions
4. Background
5. Policy
6. Guidance on Implementing this
Policy
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Basis of Traceability Policy
References
• ISO/IEC 17025:2005 - General Requirements
for the Competence of Testing and Calibration
Laboratories
• ILAC-P10 Policy on Traceability of
Measurement Results
• ILAC-G24 Guidelines for the determination of
calibration intervals of measuring instruments
• CALA A61 CALA Traceability Policy (CALA)
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4. BACKGROUND
Traceability is characterized (in ILAC documents and
the VIM) by 6 basic requirements:
• (a) an unbroken chain of comparisons going
back to stated references acceptable to the
parties, usually a national or international
standard;
• (b) uncertainty of measurement; the uncertainty
of measurement for each step in the traceability
chain must be calculated or estimated according
to agreed methods and must be stated so that an
overall uncertainty for the whole chain may be
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calculated or estimated
4. BACKGROUND
Traceability is characterized (in ILAC documents and
the VIM) by:
• (c) documentation; each step in the traceability
chain must be performed according to
documented and generally acknowledged
procedures; the results must be recorded;
• (d) competence; the laboratories or bodies
performing one or more steps in the traceability
chain must supply evidence for their technical
competence (e.g. by demonstrating that they are
accredited for that activity);
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4. BACKGROUND
Traceability is characterized (in ILAC documents and
the VIM) by:
• (e) reference to SI units; the chain of
comparisons must, where possible, end at primary
standards for the realization of the SI units;
• (f) calibration intervals; calibrations must be
repeated at appropriate intervals; the length of
these intervals will depend on a number of
variables (e.g. uncertainty required, frequency of
use, way of use, stability of the equipment).
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4. BACKGROUND
AIHA-LAP, LLC accredited laboratories must
understand the following simple relationship. All
three of these components must exist at every
level in the traceability chain in order for the final
test result to be traceable.
Calibration (1) with Uncertainty (2) produces a
measurement result that is Traceable (3)
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Basis of Traceability Policy/Guidance
Requirements
• ISO/IEC 17025, Clause 5.6
– 5.6.1 – All equipment used for tests and/or
calibrations, including equipment for subsidiary
measurements (e.g. for environmental conditions)
having a significant effect on the accuracy or validity
of the result of the test, calibration or sampling shall
be calibrated before being put into service. The
laboratory shall have an established programme and
procedure for the calibration of its equipment.
– 5.6.2 – specific requirements for calibration and
testing
– 5.6.3 – reference standards and reference materials
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• The requirement which underlies this policy is
given in ISO/IEC 17025, Clause 5.6.
• 5.1 Laboratories accredited by AIHA-LAP, LLC
shall demonstrate, when possible, that calibrations
of critical equipment and hence the measurement
results generated by that equipment, relevant to
their scope of accreditation, are traceable to the SI
through an unbroken chain of calibrations.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• 5.2 External calibration services shall, wherever
possible, be obtained from providers accredited to
ISO/IEC 17025 by an ILAC recognized signatory.
Calibration certificates shall be endorsed by a
recognized accreditation body symbol. Certificates
shall indicate traceability to the SI or reference
standard and include the measurement result with
the associated uncertainty of measurement.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• 5.3 Where traceability to the SI is not technically
possible or reasonable, the laboratory shall use
certified reference materials provided by a
competent supplier (refer to ISO/IEC 17025 4.6.4),
or use specified methods and/or consensus
standards that are clearly described and agreed to
by all parties concerned. A competent supplier is
an NMI or an accredited reference material
provider (RMP) that conforms with ISO Guide 34
in combination with ISO/IEC 17025, or ILAC
Guidelines for the Competence of Reference
Material Producers, ILAC G12. Conformance is
demonstrated through accreditation by an ILAC
recognized signatory.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• NOTE: There are many gaps in the measurement
traceability of the calibration infrastructure in the
world and there are a relatively small number of
accredited reference material providers. In
recognition of this situation, AIHA-LAP, LLC will
not require the use of accredited reference
material providers, where applicable, until January
2012. AIHA-LAP, LLC assessors will, at present,
note any nonconformity with this requirement of
Section 5.3 of this policy as a suggestion for
improvement.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• 5.4 Reference materials shall have a certificate of
analysis that documents traceability to a primary
standard or certified reference material and
associated uncertainty, when possible. When
applicable, the certificate must document the
specific NIST SRM® or NMI certified reference
material used for traceability.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• 5.5 Calibrations performed in-house shall be
documented in a manner that demonstrates
traceability via an unbroken chain of calibrations
regarding the reference standard/material used,
allowing for an overall uncertainty to be estimated
for the in-house calibration.
• 5.6 Calibrations shall be repeated at appropriate
intervals, the length of which can be dependant on
the uncertainty required, the frequency of use and
verification, the manner of use, stability of the
equipment, and risk of failure considerations.
Table 5-1 provides the minimum frequencies that
are required.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• 5.7 Periodic verifications shall be performed to
demonstrate the continued validity of the
calibration at specified intervals between
calibrations. The frequency of verifications can be
dependent on the uncertainty required, the
frequency of use, the manner of use, stability of
the equipment, and risk of failure considerations.
Table 5-1 provides the minimum frequencies that
are required.
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5. AIHA-LAP, LLC TRACEABILITY OF
MEASUREMENT POLICY
• 5.8 The laboratory shall have procedures
describing their external and internal calibration
and verification activities and frequencies, and the
actions to follow if the equipment is found to be
out of acceptable specification.
• 5.9 Laboratory staff performing in-house
calibrations and verifications shall have received
documented training.
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Table 5-1
Minimum Calibration/Verification Frequency Requirements for
Common Reference Standards and Support Equipment
Reference Standard / Equipment
Calibration Frequency
Verification Frequency
Reference Thermometer
Initial and every 5 years
Not applicable
Working Thermometer
Initial and when verification fails
Annually
Reference Masses
Initial and every 5 years
Not applicable
Working Masses
NA
Initial and then annually
Stage Micrometer
Initial and if damaged
Not applicable
Balance
Initial and following
service/repair or when
verification fails
Each day of use
Mechanical Pipettes
Initial and when verification fails
Annual
Volumetric Containers for critical
functions (non-Class A)
Not applicable
Each lot prior to use
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Table 5-1
Minimum Calibration/Verification Frequency Requirements for
Common Reference Standards and Support Equipment
• NOTE: It is imperative laboratories understand
that this table is not a list of recommended
frequencies. Rather, they are the minimum
frequencies that will be accepted by AIHA-LAP,
LLC assessors. It is the laboratory’s
responsibility to establish a suitable schedule.
68
Guidance Document and Examples
• Refer to the AIHA-LAP, LLC
Guidance on the Traceability of
Measurement for suggestions and
examples for implementing the
policies and helpful references.
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Guidance Document Includes:
• Information to help determine what
equipment needs calibration or
verification and the frequency at
which these are needed.
• Important considerations when
purchasing reference standards
and calibration services, including
content of calibration certificates.
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Guidance Document Includes:
• Considerations when performing inhouse calibrations and verifications
of various types of analytical
instruments and support equipment.
• Tables listing Uncertainty
Contributors when calibrating
balances, thermometers and
pipettes.
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Guidance Document and Examples
Uncertainty Contribution Table for Thermometers
Contribution (nomenclature)
Distribution
Estimated Value
ur
Standard uncertainty of the
nominal values of the
reference thermometer.
Normal
Expanded uncertainty on the
calibration certificate of
the reference
thermometer divided by 2
(coverage factor – k)
sp
Standard deviation of the
set of calibration
readings
Normal
Standard deviation of the set
of calibration
measurements.
u1
Standard uncertainty of the
readability and
resolution of the
working thermometer
Uniform
(Square)
Smallest gradation of the
working thermometer
divided by √3. Use
ONLY if Sp = 0
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Guidance Document and Examples
Uncertainty Contribution Table for Pipettes
Contribution (nomenclature)
Distribution
Estimated Value
ur
Standard uncertainty of the Normal
nominal values of the
reference balance.
Expanded uncertainty on
the calibration
certificate of the
reference balance
divided by 2 (coverage
factor – k)
Sp
Standard deviation of the
set of calibration
readings
Normal
Standard deviation of the
set of calibration
measurements.
ST
Standard deviation of
corrections caused by
temperature (∆T) when
the temperature differs
from standard
o
temperature (20 C). The
thermal coefficient of
expansion of water is
0.00021 per 1° Celsius at
20° Celsius.
Uniform
(Square)
Relative Standard
Deviation = (∆T x
0.0002) / (√3) in
millilitres per millilitre
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Guidance Document and Examples
Uncertainty Contribution Table for Pipettes
Contribution (nomenclature)
Distribution
Estimated Value
u1
Uniform
(Square)
Smallest gradation of the
working volumetric
instrument divided by
√3. Use ONLY if Sp =
0
Standard uncertainty of
the readability and
resolution of the
working volumetric
instrument
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Additional Guidance Document
Content
• Guidance on how to find an ILAC
recognized accredited calibration
laboratory.
• Guidance on selecting reference
material providers, including
sources for identifying those that
are ILAC recognized.
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Guidance Document and Examples
Example Excel calibration worksheets are also
found on the AIHA website.
Key concept to remember: traceable
calibration must also include uncertainty.
• Calculate the combined uncertainty
SDc = √ [ SD12 + SD22 + … + SDn2 ]
• Calculate the expanded uncertainty
Apply a coverage factor ‘2'.
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Summary of Traceability Policy
• Section 5.1 requires laboratories to demonstrate,
when possible, that their analytical results are
traceable to the SI (International System of Units)
through an unbroken chain of calibrations within the
measuring system. This requirement can be met for
weights (masses), balances, thermometers,
volumetric ware (e.g., mechanical pipettes) and
stage micrometers.
• Section 5.2 expands upon the required information
that must be included in calibration certificates
received from accredited external calibration
services.
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Summary of Traceability Policy
• Section 5.3 details requirements for providing
traceability of analytical results when traceability to
the SI is not possible (most chemical and
microbiological analyses). Included are
requirements for providers of reference materials.
Because there are currently only a few accredited
reference material producers, use of these
producers will be encouraged where available but
not mandated until 2012. Traceability options using
specified methods or consensus standards are also
provided.
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Summary of Traceability Policy
• Section 5.4 requires certificates of analysis for
reference materials and defines information that is
required on the certificates.
• Section 5.5 addresses documentation required for
in-house calibrations and requires these calibrations
to include an estimation of the overall measurement
uncertainty.
• Section 5.6 requires laboratories to establish the
frequency at which calibrations will be repeated. A
table of minimum calibration frequencies for
reference standards and support equipment is
included.
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Summary of Traceability Policy
• Section 5.7 requires laboratories to also establish a
frequency for and perform calibration verifications to
demonstrate the continued validity of the calibrations. A
table of minimum verification frequencies is provided
• Section 5.8 requires laboratories to have procedures that
describe internal and external calibration and verification
activities and their frequencies. These procedures must
also describe the actions to be taken if equipment is
found to be performing outside of acceptable
specifications.
• Section 5.9 requires laboratories to maintain
documentation demonstrating that personnel who
perform in-house calibrations and verifications have been
trained to perform these activities.
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As of April 1, 2010
• Traceability procedure(s) must include all elements
from the AIHA-LAP, LLC policy.
• The procedure(s) must be implemented.
• All equipment must be considered and those with a
significant impact on test results should be dealt
with in a defensible manner.
• The calculations used follow the MU policy
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Next Steps
• .25 CM points were granted for the
March 11 MU and Traceability Webinar
– Will also apply for CM points this Webinar
• We are collecting questions from both
Webinars with the goal of developing a
FAQ to post on the AIHA-LAP, LLC
website in late June.
• Thank you for participating!
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Questions?
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