ISO/IEC 17025:2017 Decision Rules and their Application to Meeting the Requirements
Summary
TLDRこのウェビナーでは、Perry Johnson Laboratory Accreditationのマイケル・クレイマーが、ISO 17025:2017の要件を満たすための決定規則とその応用について説明します。彼は、測定不確かさを考慮に入れる方法と、顧客との合意の重要性に焦点を当て、さまざまな決定規則の例とそれらがどのように適用されるかを紹介します。また、リスク管理の新たな要求事項と、ラボが柔軟で顧客のニーズを満たすための手順についても触れています。質問応答セッションを通じて、決定規則の概念に関する参加者からの疑問に答え、次回のウェビナーについても紹介しています。
Takeaways
- 🔑 ISO 17025:2017では、測定の不確かさを考慮して適合性の判定を行う際の「決定規則」を定義し、顧客と合意する必要がある。
- 🤝 決定規則は、契約レビュー段階で顧客と合意し、文書化する必要がある。
- 🎯 決定規則には、単純な合否判定だけでなく、条件付き合格や不合格などの複数の判定レベルを設定できる。
- ⚖️ 決定規則には、偽陽性(不合格品を合格と判定)や偽陰性(合格品を不合格と判定)のリスクレベルを考慮する必要がある。
- 📚 一部の試験方法や規格では、決定規則がすでに規定されている場合があり、その場合は別途の決定規則は不要。
- 🔍 測定の不確かさを無視する「単純受入れ」の決定規則を適用する場合、その旨を文書化し、偽陽性や偽陰性のリスクを最大50%と見なす必要がある。
- 📝 報告書には、適用した決定規則と関連するリスクレベルを文書化する必要がある。
- 🔄 内部顧客に対しては、結果の報告を簡素化できるが、必要に応じて不確かさの影響を追跡できるよう記録を残す。
- 🧩 顧客が適合性の判定を必要としない場合は、決定規則の文書化は不要。
- ✨ 決定規則の適用は柔軟性が求められ、顧客の要求事項を満たすために各検査機関がケースバイケースで対応する必要がある。
Q & A
決定規則とは何ですか?
-決定規則とは、測定の不確かさを考慮して、規格への適合または不適合の判定をする際の基準を定めるルールのことです。ISO 17025:2017規格で新たに導入されました。
なぜ決定規則が重要なのですか?
-測定値だけでは規格への適合性を適切に判断できない場合があるため、測定の不確かさを考慮する必要があります。決定規則はこの不確かさを考慮した上で適合性を判定するルールを定めるものです。
決定規則はどのように適用されますか?
-契約レビューの段階で顧客と決定規則について合意し、そのルールに従って結果を報告する必要があります。単純な合格/不合格判定だけでなく、条件付き合格/不合格などの複数の判定区分を設けることもできます。
決定規則は誰が定めるのですか?
-試験所または校正機関が決定規則を定め、顧客と合意する必要があります。試験方法や規格によっては、決定規則が既に定められている場合もあります。
測定の不確かさを考慮しない場合はどうなりますか?
-測定の不確かさを考慮しない単純な合格/不合格判定では、不適合品を合格と誤って判定する(受入れる)リスクや、適合品を不合格と誤って判定する(拒否する)リスクが高くなる可能性があります。最大で50%のリスクがあると言われています。
決定規則は校正証明書にどのように表記されますか?
-決定規則の詳細は校正証明書に記載する必要があります。判定基準となる許容範囲、不確かさの扱い方、合格/不合格の判定区分、各判定区分のリスクなどを明記します。
決定規則は内部顧客にも適用されますか?
-内部顧客の場合、決定規則の適用は必須ではありませんが、後から測定の不確かさを評価できるようにしておく必要があります。外部顧客には決定規則を適用し、契約時に合意を得る必要があります。
特定の試験方法に決定規則が組み込まれている場合はどうすればよいですか?
-試験方法に決定規則が組み込まれている場合は、その規定に従えばよく、別途決定規則を定める必要はありません。ただし、顧客との合意は必要です。
決定規則を適用しない場合、どのようなリスクがありますか?
-決定規則を適用しないと、不適合品を誤って合格と判定したり、適合品を誤って不合格と判定したりするリスクが高くなります。このようなリスクを顧客に伝え、合意を得る必要があります。
決定規則の選択や適用に関するガイダンスはありますか?
-ILACのガイダンス文書G8には、決定規則の選択や適用に関するガイダンスが記載されています。さまざまな事例や計算例が示されているので、参考になります。
Outlines
😀 開会の挨拶と導入
スピーカーのMichael Kramerによる開会の挨拶とwebinarの目的の説明。本webinarはPerry Johnson Laboratory Accreditationから行われており、参加者にはwebinarの録画とスライドが後から提供される予定。本webinarのトピックはISO 17025:2017における決定規則とその適用であり、主に校正プログラムについての内容になる。
🧐 決定規則の要求事項
ISO 17025:2017では、顧客が規格や仕様への適合性の判定を要求した場合、その決定規則を明確に定義し、顧客と合意する必要がある。決定規則は契約レビューの際に協議され、同意を得る必要がある。決定規則は、測定の不確かさを考慮に入れる方法を説明するものである。顧客の要求に柔軟に対応できるよう、手順を定めることも規定されている。
📚 ILACガイダンス文書について
決定規則に関するILACのガイダンス文書G8が最近発行された。この文書は、ISO 17025:2017の規格や仕様への適合性の判定に際して、どのように決定規則を適用するかについてのガイダンスを提供している。決定規則の定義と、ガードバンド、簡易受入れ、テスト不確かさ比(TUR)などの関連用語についても説明されている。
🔍 規格や試験方法に決定規則が含まれている場合
一部の規格や試験方法には、既に決定規則が組み込まれている場合がある。例えばASTM E84、ASTM A29などでは、手法の中で決定規則が定義されており、さらにガードバンドを追加する必要がない。ISO 14253などの規格でもガードバンドが組み込まれている。このような場合は、規格や試験方法に従えば良い。
📐 決定規則の要件
ISO 17025:2017では、適合性の判定において測定の不確かさを考慮に入れることを求めている。通常は95%信頼の下限値(k=2)が用いられるが、場合によっては99%信頼の下限値(k=3)を要求されることもある。測定値と許容限界の関係によって、単純受入れ、不適合、条件付き適合などの判定結果が生じる。
💯 単純受入れの決定規則
顧客が単純受入れの決定規則を希望し、合意した場合、測定値が許容限界内にあれば適合、外にあれば不適合と判定する。この場合、測定の不確かさは考慮されず、偽認証や偽棄却のリスクが最大50%となることを顧客に伝える必要がある。
🎯 ガードバンドを用いた決定規則
顧客がガードバンドを用いた決定規則を希望し、合意した場合、許容限界の内側にガードバンドが設けられ、適合、条件付き適合、条件付き不適合、不適合の4種類の判定が行われる。この場合、偽認証と偽棄却のリスクは2.5%以下に抑えられるが、許容限界付近では最大50%のリスクとなる。
✅ その他の決定規則の表記例
顧客と合意の上で、測定不確かさを考慮した上で、偽認証/棄却のリスクが5%を超えない場合のみ「適合」と報告する決定規則を採用することも可能である。単純で明確な表記方法として、「測定値±測定不確かさ」が仕様内に完全に収まる場合のみ適合と判定するという決定規則もある。
⁉️ 決定規則が必要ない場合
適合性の判定が必要ない場合は、決定規則を報告する必要はない。しかし、顧客から適合性の判定が求められた際は、契約レビューの際に決定規則について合意を得る必要がある。また、一部の試験では決定規則が不要な場合もあるが、その場合は顧客との合意が重要である。
🔚 まとめと質疑応答
プレゼンテーションのまとめと、参加者からの質問に対する回答。決定規則を適用しない場合は、顧客との合意が重要であること、決定規則は契約レビュー時に合意する必要があること、内部顧客には簡易報告でも構わないことなどが強調された。特定の試験方法については回答が難しい場合があるが、ILACのガイダンス文書を参照するとよいことが説明された。
Mindmap
Keywords
💡決定規則
💡測定の不確かさ
💡合否判定
💡契約レビュー
💡リスク
💡ガードバンド
💡IALGガイダンス文書
💡規格の引用
💡内部顧客
💡試験手順
Highlights
Michael Kramer introduces the webinar on behalf of Perry Johnson Laboratory Accreditation, focusing on the decision rule and its applications to meet ISO 17025:2017 requirements.
The webinar emphasizes the importance of decision rules in the context of ISO 17025:2017, highlighting their role in accounting for measurement uncertainty in statements of conformity.
Introduction to the concept of decision rules, explaining how they have always been a requirement but were not previously defined until the 2017 standard.
Explains the necessity of defining and agreeing on decision rules during the contract review process with customers.
Discussion on whether a default decision rule can be applied and how it must be presented and agreed upon during contract review.
Highlighting the flexibility required in applying decision rules to accommodate various customer requirements and the diverse applications of tests and calibrations.
Illustration of how different applications (e.g., DNA testing, public health, educational purposes) require different levels of risk acceptance in decision rules.
Emphasis on the laboratory's responsibility to review customer requests and ensure the selection of appropriate methods and procedures.
Introduction to guidance document ILAG G8, aimed at assisting laboratories in using decision rules for declaring conformity with specifications or standards.
Explanation of guard banding and its relevance to decision rules, including the concepts of simple acceptance and the test uncertainty ratio (TUR).
Discussion on the expanded role of measurement uncertainty and decision rules in the 2017 version of ISO 17025.
Clarification on the application of decision rules in both testing and calibration, with examples from ASTM standards.
Exploration of different decision rule approaches, including binary and non-binary statements, and the implications for risk of false acceptance or rejection.
Details on how to document decision rules on calibration or test reports, emphasizing the importance of agreement with the customer.
Q&A session addressing specific questions about decision rules, measurement uncertainty, and reporting requirements.
Conclusion of the webinar with a reminder about the availability of the recorded session and slides on Perry Johnson's website.
Transcripts
hello welcome my name is Michael Kramer
I am presenting this month's webinar on
behalf of Perry Johnson laboratory
accreditation I want to thank everybody
for logging in and listening to us this
afternoon or this morning depending on
where you're happy to be located
I am the calibration inspection program
and repeat in LA and this month I will
be presenting on the decision rule and
their applications to meet the
requirements of ISO 17025
2017 they're with me I'm having a little
problem getting to my starting point
all right sorry about that folks
this webinar is being recorded all the
webinars are recorded you can go online
at the Perry Johnson's website PG laughs
comm go to the tide recorded webinars
surely when we're completed here and
that was a Friday have some colleagues
that may have started their weekend a
little are only had perhaps would
appreciate the fact they can go on our
website and listen to today's
presentation also the individual slide
will also be available on our website go
to the webinars tab and you will see the
time for just a slide presentations and
there's no need to email me and asking
for the slides they are available upon
our website along with the recording as
always that you can answer you can ask
questions during the course of this
webinar we'll entertain them at the
conclusion you should have a box there
on your screen again please keep your
questions related to today's topic
today's topic a decision rule it's going
to vary on how that's looked at
particularly among you folks in testing
just bear in mind I am a calibration
individual if your very program specific
in regards to say perhaps a specific
tester doing I may not be able to answer
your question hopefully I will answer a
lot of those during the course of this
presentation so a decision rule so what
is that should be nothing new there was
a requirement in the 2017 and
incorporations decision rule it was
there however it was never defined so
the 2017 standard is one of the
definitions that that the standard has
encompassed and you can see the
definition of a decision rule is a role
that describes how measurement
uncertainty is accounted for when making
statements of conformity with a
specified requirement when I said that
was always been a requirement we have an
Clause from the 2005 standard
underreporting so whenever you made that
statement of compliance the measurement
excuse me the uncertainty of measurement
shall be taken into account X that's
what the decision rule is as you can see
by the definition it's how it's taking
into account so you'll see it's a
magnified in 2017
so the decision rule first makes its
appearance in the 2017 after that
definition the ones in the section 4
review request tenders and contracts so
under clause 7 1 3 when the customer
requests a statement of conformity to a
specification or a standard for a test
or calibration and what we're saying
then you'll see this further clarified
in this presentation if your report is
making a statement such as pass/fail
intolerance out of Tolerance that's a
statement of conformity the decision
rule shall be clearly defined unless it
heard it in the requested specification
or standard the decision rule shall be
communicated to and a key word here is
an agreed with the customer so the key
is also when it's requested which
implies it is requested by the customer
this means that the contract review must
must take place and a clear indication
agreed on before the job is started so
instant decision rule should be
discussed and agreed to up in the nor
any a contract review process
so I proposed the question can there be
a default decision role taking or leave
and sort of approach and I have good and
we're doing more and more assessments
now of course to the 2017 standard folks
are transition tune is going to expire
in roughly a year so most everyone who
is having their assessments now when
we're coming on site is to the new
standard so I've seen this before a
decision wrong with default decision
rule prevent it during contract remote
review and of course I would say if a
customer sees that and agree and agrees
to that then you're fulfilling the
requirement during contract review that
is presented and agree to one thing I
like to specify here with the decision
rule however laboratory you'll see here
some clauses where the laboratory needs
to be flexible and if they have the
capabilities to meet the requirements of
the customers
this is specified in other parts of the
standard also I just want to have an
example here so uh what size may not fit
at all so you may have a varied array of
clients so it's about an example here of
a pipette so under these various
examples here a pipette can be used for
DNA testing in a crime lab - yeah like
that can be used for it's uh could be
used in a court of law in other words
the results of any sort of testing that
that pipette was used for public health
the pipette that can be used to test
drinking water for example or else a
pipette can be used perhaps in a
chemistry class or some other rough
estimation of delivered volumes so I
would say
based on these circumstances the left
excuse me the rebel of list of false
acceptance would not be the same and
some of your customers may have very
very different criteria for defining how
the decision rule is applied in
reporting their statement of compliance
so again the standard is also as far as
meeting customers requirements being
flexible the lavatory shall have a
procedure for reviewing request tenders
in contracts does wherever the decision
rule first appears and under the the
procedure shall ensure that the
appropriate methods and procedures are
selected and are capable of meeting the
customers requirements also the lavatory
shall cooperate with customers
representatives even clarifying the
customer's request and in monitoring the
laboratories performance in relation to
the work performed under structural
requirement so the habit reactivity
shall be carried out in such a way as to
meet the requirements of this documents
in the laboratories customers regulatory
authorities and organizations providing
recognition laboratory manner in which a
community shall ensure the communication
take place regarding the effectiveness
the management system and the importance
of meeting customers and other
requirements and also under reporting
the results shall include all
information agreed with the customer and
necessary for the interpretation of the
results and all information required by
the method used also some flexibility
may be needed in regards to risk which
is now a key factor and actually an enum
of section within the 17.25 standard so
custom
which operate both 1/3 1/7 go to five
and also you may have clients that are
now presented wrists in ISO 9001 2015
where they're looking at that that risk
perhaps more closely the risk of false
acceptance of making a statement of
compliance on their tests or calibration
reports so they're on 9001 six point one
that's where that there's require miss
Norris actions taken to address risk and
opportunities shall be proportional to
the potential impact on the conformity
of the products and services and of
course on the 1 702 5 Section 85 is a
new requirements concerning risk so if
you happen if you're at calibration lab
and you're doing working work perhaps
for a testing lab they don't know how as
per Section eight five the laboratory
shall consider the risk and
opportunities associated with laboratory
activities so well shortly after I began
writing this presentation a guidance
document came out so I want to bring
your attention to this I have
incorporated some of the ideas behind
this guidance document into my
presentation today this is an I'll a
guidance document G documents G stands
for guidance they're different than the
P documents which are policy documents
which pjl AR PL 1 2 P L 3 PL 4 stem from
I lack policies this is a guidance
document I was able to get hold of this
and review it just hot off the press so
this guidance document has been prepared
to assist laboratories in the use of
decision rules when declaring statement
of conformity to a specification or
standard
that's required now in 175 the revised
one 705 2017 recognizes that no single
decision rule can address all statements
of conformity across the Bombers scope
of testing and calibration and 175 is
for testing and calibration and there's
multiple types of testing the
calibration of course that folks under
our accreditation are accredited to
perform so a couple definitions I did
these are brought forth from the
guidance document it comes up but often
with decision rules the concept of a
guard banding the interval between
e-collar aslam it and a corresponding
accept lease limit where that accept
this living is the tolerance limit with
an acceptance limit which is guard
banded there's something called simple
acceptance this is a decision rule in
which the excess subject acceptance
limit is the same as the tolerance
limits so if you look at that and you
think about that that implies no guard
Manning that is called simple excuse me
simple acceptance term you see often
used a lot with uncertainty and
tolerance is a TR ratio test uncertainty
ratio and that is the ratio of the
tolerance of a measured quantity divided
by this is assuming your K equals to 95%
which those born cases they are divided
by the 95% expanding measurement
uncertainty of the measurement process
there's your formula they're left on at
the bottom of this slide for those folks
that are interested you can always
google it
the I like g8 document is free you could
get it right off the I lack website i do
go over some examples here I don't cover
the whole document so if you like to
that is a resource there that I'm
presenting here and there is the direct
link to all the guys excuse me to all
the I like guidance document and from
that page you can of course go directly
to g8 you might find some other
interesting documents there as well so
of course one seven oh two five and
includes criteria related to decision
rules in conformity with requirements
and resources and processes or lady to
we'll see in personnel we've already
talked about contract review it's
addressed right up in the front there
that's media agreed to up front and
reporting is described below again I
have the decision rule definition here
which is the clause three point seven in
the standard under personnel six to six
it requires that old laboratory shall
authorized personnel to perform and now
this results including statements of
conformity or opinions and
interpretation and son this individual
who's authorized to analyze these
statements that conformance should be
versed in the decision rule and of
course there are applications and of
course reporting so we basically saw in
the old 2005 standard when you make a
statement of conformity measurement
uncertainty had to be taken into account
so we'll see some I haven't per made
them here from the standard how that's
expanded particularly in the reporting
of results so when a statement of
conformity to us
specification or standard for a test
calibration is provided the laboratory
shall document the decision were
employed taking into account the level
of risks such as false accept and false
accept statistical assumptions
associated with the decision rule
employed and apply the decision rule 786
- requires that lavatory shall report on
a statement of conformity such as the
statement clearly identified over which
results the statement of conformity
applies which specification standards
are part thereof or met or not met and
then last but not least the decision
role unless it's inherited in the
requested specification or standard so
you can see yeah quite clearly here the
concept of taking measurement
uncertainty into account they greatly
expanded into 2017 standard one thing I
want to expand along these next two
slides if you look at clause 786 to see
this general rule applies and we have in
parentheses there unless isn't heard and
in the requested specification or
standards and those folks that are
involved in testing often this is a
Patrick all the various testing types of
tests and decision rule actually
incorporate it within the procedure only
the NC stays the laboratory shall report
on the statement and conformities such
as the statement clearly identifies it
is a senior rule so what does this mean
unless isn't hurried in the requested
specification or standard I have a few
samples here sure there's quite a few
others but for example there are testing
methods that determine how the rules are
applied one good common illustration is
ASTM e 84 Rockwell artists for the
testing and calibration decision rules
take uncertainty into account
effectively and the repeat testing in
other limits as a spread of the data
etc and the rules are defined within the
methods another example in is ASTM a 29
which is standard specification for
general requirements of steel or carbon
and alloy hot Walt where it is an an
auxilary table that is based on the
method on 30 to give some extra rooms to
make a decision and this comes right
back I like guidance document g9 stays
if your application already has
measurement decision rules governed by a
public standard guidance document just
some examples here ISO 1 4 2 5 3 8 6 5 5
6500 8 etc generally in those cases case
standard test methods are prescribed and
off its compliance limits already have
garbade's built into limits so any
further garb aiding to limit risk is not
necessary like I said this is that many
encompass some of you testing folks out
there may be already handled within the
test method calibration I believe is
pretty straightforward as far as a
decision rule
reporting how it should be agreed to and
then of course documented on the
calibration report is stated in the one
702 five standard sewing for those folks
even on the test again even if you
perhaps are not so much having to handle
each individual test with garb any
perhaps you have tables where it's
already built in you may also be on the
other end where you have equipment that
you're taking out to have calibrated
these mean traceable calibration heads
you need even if that's already built
into your your method if your your
encompassing that you may encompass
decision rules and have it to agree to a
decision rule with your calibration
provider now so a decision rule for
proving conformance or nonconformity
with a specification makes a
differential or other conformance or non
conformance shall be determined with a
high probability so typically will see a
K equals two or a 95% confidence
interval associated with uncertainty and
often documented on the calibration
report the expanded measurement
uncertainty you and a confident level of
across we ninety-five percent expansion
factor K equals two will genuinely be
considers as adequate there may be cases
that would require a higher confidence
level 99 percent for example and and by
prior employment I have some cases I do
recall where the folks who I was
providing calibrations for or very
versed on measurement measurement
uncertainty at the K equals two and
there were some cases I can recall
mostly dealing with those that are used
in a court of law such as that slide
with the DNA testing crime labs in other
words requiring that K equals 3 or a 99%
k factor so typically with the
measurement uncertainty is typically
calleb is typically reported at a 95%
confidence interval which is what that
example is doing at the body because
he's very close is taking into account
the t-distribution degrees of freedom
and it multiplies that expanding
uncertainty times this this case the T
value of 2 giving you that 95%
measurement uncertainty plus or minus
95% confidence interval so what are we
talking about here I mean this might be
the very basic for some folks that are
listening but when we're talking about
taking measurement into account here's a
basic case where we have a description
description here what we have for
different cases so you can see case ABCD
we have that triangular type is the
actual value and this is on either side
that's that gray area of uncertainty so
typically say that case 1 and what the
upper and lower limits are representing
here or the tolerance so for something
to be saying within specs it's got to be
within the upper and lower limit so that
first case second case if you look at
the values only the values are clearly
with him
if you look at case C and D if you just
look at the values only they were
clearly out of sex so when we look at
uncertainty you seek uncertainty aids
around the value more effects the
statement he complies when those values
are close to the tolerance limits so for
example case B the value is within
however the uncertainty that gray area
actually strays to it being out of both
the upper and lower limit they KC also
now use in clearly if you're basing your
decision just bare just based on that
value you would say that was out of
Tolerance Hale does not pass however
taking measurement uncertainty into
account it can actually if you're just
basing it on a value you can actually
make it a statement of false except
where measurement uncertainty would
affect that statement of compliance case
D is clearly out of tolerance value eyes
and also take your measurement
uncertainty into account
so I have some examples here from the I
like guidance document here where it
talks about a binary decision rule that
is a eith where you make a decision
based on a simple pass and fail so you
see here and this is for simple
acceptance if you recall simple
acceptance is where we are basically
we're not thinking measurement
uncertainty into account so in this case
if this is you're doing a primaries that
statement of simple acceptance rule
without Gore banding all four of those
cases you clearly state a pass fail so
if we look at the second one over for
example we must think that as passing
because the value is within
specifications however taking the
measurement uncertainty into account
they actually affect that decision again
with this if you're doing this again
this needs to be accepted to and agreed
to by your customer upfront during
contract review so this is just a simple
pass/fail AC on the measurement value
without regard to guard banding again
this is further depicting even if you
are and this is just taking that
previous example a little further if you
are guard banding and you're doing
simple acceptance you can see even with
the GAR banding you still specify just
those two decisions either a pass or a
fail
here are examples of a non-binary
statement with guard Mandy
so in this and these instances decision
rules exist when multiple terms may
express the results in this case here we
have conditions that could be a clear
pass a conditional pass a conditional
fail in a straight out fail so you can
read the documentation there what we're
referring to but basically what this is
doing is for example under the
conditional pass that's a statement you
would refer to on your report in this
instance you're not stating his pass
you're referring to it as a conditional
pass we're going to look at the waste
document is here in a little bit as far
as that this is a real statement looking
at the conditional pass we have a Garbi
in there so our value it's not it's
between the guard being where we are
beating against uncertainty and the
actual tolerance limit so that's the
case where it may pass but it may not
pass if you take measurement uncertainty
to account hits you can coined a phrase
conditional pass for those of you all
who is accredited with us we actually
address this currently we have not
revised any of our policies of Perry
Johnson right now in regards to the
revision of the standard we refer to
this we do give a little guidance on
this and pl3 that's measurement
uncertainty we refer to that condition
if you like it better as possibly
terminate or fail and determinate so in
these cases here you're not going to
clearly stay
pass or fail what measurement
uncertainty affects that statement in
compliance
examples of decision rules so here is an
example if you customer has agreed to it
up front a simplified acceptance rule
which is basically you're not going baby
so if a customer agrees that a pass/fail
decision or based on acceptance limits
chosen based on simple acceptance where
you're basically you're you're basically
just looking at the tolerance limit
there the expanding measurement
uncertainty calculated is calculated
Colonel Gumm guide that unsturdy a
measurement must be less than a third of
the tolerance based on manufacturer
specs we talked about t you are that
ratio is three to one statement of
conformity or mining binary the estimate
of the measurement is assumed of a
normal distribution is specified risk is
used for the risk calculation now in
this case if you are doing a your
customer has agreed to this simple
acceptance type role the risk of false
accept is is up to 50% for measured
results excuse me up back up a little
bit it could be 50% in the case that
accepted accept excuse me I accepted
items or outside the tolerance limit our
false reject if it's outside can be up
to 50% so that's the decision rule that
would need to be documented in this case
if you're not taking measurement
uncertainty into account so where are we
coming up with 50% that is in the
extreme case it says up through there so
if you figure if you're right on the
cholera's limit as far as a pass or fail
measurement uncertainty is a value plus
or minus a degree of uncertainty that's
a 50/50 when you look at it and you
think about it that way
so the risk of loss accept is
in this case if you're using a simple
acceptance role to be up to 50%
it's the decision role with that what
need to be documented here is a
simplified acceptance decision role with
you have to take into account the risk
of false accept or reject which we'll
see here shortly that in this case is up
to 50% here we have the armaiti example
where we have more than one excuse me
more than two decisions so this is where
we have the conditional past conditional
fail and that's saying this is an
example that that you're employing in
your lab and the customer agrees that
decision rules are based on garb a and
accept this limit where your car banning
the tolerance against those against the
entity except this limits being or
baited with the uncertainty where you as
the expanded measurement uncertainty
calculated for the gum standard of
conformity or not very non-binary the
estimate of the measure is assumed to
have a normal probability distribution
in risk is used for the risk calculation
in this case the risk of acceptance
items to be outside the tolerance limit
is less than 2.5 reject percent for a
rejected items the risk to be inside the
tolerance limit is less than 2.5 percent
when the measure result is close to the
collar it's limit the risk of false
accept and reject is up to 50% then I'll
expand on that a little bit so what that
is it's a little bit confusing when you
look at that but if you say something is
in the acceptance level
and I say it's right on that limit and
this is based on a 95% confidence
interval it's plus or minus so you're
gonna go plus 2.5% into that conditional
pass zone hence that leaves an
additional 2.5% where you could be
making a decision of false acceptance
when you are basically stating something
passes again the 50% that would be in
those cases where it falls directly on
the tolerance or the acceptance limit
there so here we have four different
criteria we have accept conditional pass
conditional bail well we also have a
rejection interval so here we're gonna
have several different decision rules
that should be expressed on your
calibration report if you are calibrator
so we would specify and we're stating
something that passes the measure value
were observed in tolerance at the points
tested the specified false accept is up
to 2.5%
what identify conditional pass the
measurement values were observed in
tolerance at the point tested however a
portion of the expanded measurement
uncertainty intervals that one of the
more measure values exceeded tolerance
when the measurement result is close to
the tolerance the specified false accept
is up to 50% and then here is just the
reversal on the other side that defies
the decision rule for a conditional fail
or something might accept barely fail
however it could fall over into the past
category would be a appropriate decision
role statement to define that and there
was those values that clearly fail
values were observed out of tolerance at
the point test at the specified false
reject is up to
five percent excuse me 2.5% okay so uh a
couple other common decision rule
statements perhaps you don't like the
concept of the conditional pass/fail you
want to report a pass or a fail you just
want to garb and let's say against the
five percent excuse me the five percent
of possibility of false acceptance or
false objective rejection so I have a
couple other decision rule statements
that are perfectly okay if of course
your customer agreed to it accounting
for the uncertainty will take that taken
to me that in a 95% confidence level the
measurement result plus or minus the
expanded uncertainty equals two shall be
totally within the specification limit
and the risk of false accept / rejection
will not be greater than five percent or
even more simpler the results cannot be
reported as being in specification if
the risk of false acceptance / reject
and the customer is greater than five
percent so we have to take the level of
risk into account with these decision
rules and that's the requirements data
right there in 76112 statement of
conformity to a specification or
standard is provided the lavatory shall
document the decision trowing coin they
can add it to account take it into
account the level of risk so the risk
word pops up here such as false accept
false reject and the statistical
assumptions associated with the decision
rule employed and apply the decision
rule
okay there may be cases your might be
thinking I have a completely different
application where this you may have
customers where the uncertainty or
decision rule would be very Manute or
may not really apply to them in their
areas of testing or calibration like
anything I just want to point it out if
the word if for whatever reason these
are requirements ignoring the seven
point eight one of the very first
requirements it talks about is
simplified reporting and that's based
that is based on what agreed with the
customers a results may be reported in
this simplified way and Eve any
information listed between the clauses
seven eight - seven eighty seven that is
not reporting to the customer shall be
readily available so that was also
specified at 2005 2005 specifies a
written agreement 2017 does not I would
suggest however if for whatever reason
you're bypassing this it needs to be
agreed to up front and I would capture
that in writing
create a record then it was agreed to
between you and your customer so
sometimes this isn't that this may apply
very coarse testing destructive testing
just there are example of a furniture
test on the the far left side are saying
like a truck scale calibration thousand
pound blocks of motorized
weight cart used on a scale with 24
graduations
okay that concludes today's presentation
we will pause here for a second like I
said I hopefully have looks like I got
some questions here I will try to answer
as many as I can
hi is it also a decision rule not to
take the measurement uncertainty into
consideration in the laboratory and the
customer negotiate this in a way um
again you know I try to emphasize here
you need to agree to it upfront you know
your customers are better than I do
you need to be flexible with it there
are parts of the standard or you need to
meet your customers need but but
absolutely I'm that the key here is you
need to come to an agreement and I'm
just rereading the question and what
you're talking about here is that simple
acceptance where you're not thinking you
didn't do like you so if that is the
case however let's recall that needs to
be documented on the calibration report
that decision rule and it needs to take
into account the level of risk which we
depict there when we went over that
slide that could be up to 50% so if you
and your customer has come to that
agreement that's fine and you also need
to look at it perhaps your reporting the
uncertainty your reporting just a PI's
plan without taking it into account your
customer may very well be able to make
that decision for themselves looking at
the value looking at particularly those
that are close but determining whether
or not measurement uncertainty would
affect that decision and whether or not
that would affect
perhaps their own testing or calibration
that they do in regards to the artifact
that the perhaps that are sending to you
all
I'm trying to read this next question or
contract lavatories required to provide
statements to conformity when requested
by the client if not can a lavatory
choose not to provide this service and
therefore have no need for a decision
rule well absolutely
if you're armed and I recently came
across this on an assessment laboratory
decided that they're going to report the
values without making a statement of
compliance well the very first thing yes
if your customer agreed to that up front
and you're reporting hey this is let's
say a test weight for example this is
the value of your 1 gram test weight one
point zero zero zero zero five grams and
your uncertainty is plea 0:02 milligrams
and you are not stating a pass or fail
there then the decision there is no
decision rule to be documented on the
report that is just when you're making
that statement of compliance that is
city rule needs to be there so if for
whatever reason you are not reporting in
decision you are not reporting a
statement it complies on the report then
there is no decision rule there
[Music]
all right now actually if a customer
asked to see only the readings that fall
outside the outer tolerance limit plus
the uncertainty garlanded as a fail on
the certificate that is okay again you
have to I'm not showing I'm capturing
the whole gist of the question that's
perfectly fine except you still have to
deter key you still have to document the
decision roll with the level and it
looks like you're talking about just on
the failure side with the level of false
acceptance so if you're actually guard
banding those failures
that's that K equals 2 or 95% confidence
interval you still need to document that
level of false except excuse me of a
false rejection in that case
if the customers are internal and don't
require pal Labs is for the purpose of
the pass or fail the product and I'm
reading this exactly this pipe and if
I'm missing part of the question there
so if you have an internal customer
internal to your organization and
basically with those reporting no you
don't have to report the decision rule
that simplified you're looking at
simplified reporting their play States
or internal customers and agreed to by
external gusted customers but we're
going to backtrack a little bit the
records you have to maintain the records
where where need be go back and
determine whether or not measurement
uncertainty may actually affect a
statement it complies but for internal
customers you have a lot of wiggle room
there as long as you've been tainting
the records where you could go back and
do the reverse traceability and see if
it actually affects the result so that
would go with anything you reporting the
results for internal customers they can
all be reported in any I simplified
manner
and that's the next question and this is
an area I'm not familiar with it all as
a testing he's referring to Eliza I know
what that is but as far as a testing
protocol I'm not familiar with negative
controls are always run with unknown
sample the kits provide a clear value
after which results are declared
positive that do you think we need to
draw a decision rule for our results and
you asked me what I think I think that
sounds like one of those areas that may
be incorporated within the test method
how that that ascorbate it against but
again I really don't know in that
particular instance
we're making those statement in
compliance on the certificate is no
statement regarding the decision rule
required now if you're not making a
statement in compliance there is no
decision rule statement to be made just
bear in mind if your customer requires a
statement of compliance which yeah you
need to determine it is specified in
section 7 1 under review request tenders
and contracts if it's determined or that
they don't need a statement of
compliance on the report say the value
and the measurement uncertainty is
sufficient you're not making a statement
of compliance
hence no decision rule is needed like I
said you know your customers better than
I do and that might be fine for perhaps
99.9 percent of them all right very good
questions there again now this
presentation will be available on the
I'm still getting questions nope before
I sign off just want to we already have
next what next month's webinar which is
Friday October 25th one o'clock and
we're going to look at two through the
first two sections in the 2017 standards
also expand in a one-for-one
impartiality for to confidentiality
again this presentation is available
will be available shortly on our website
the recorded version the slides will be
there as well and again that I lack
guidance document g8 that's new that was
just released there's a lot of good
information on there so if you further
reading and there's other examples
stated in there that could all I think
is an excellent resource for
particularly you calibrators to take a
look at so again real good questions I
appreciate everybody logging in I
appreciate your interest
I look forward to doing this again next
next month again enjoy the rest of your
day
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