This document discusses practical approaches for estimating measurement uncertainty in environmental laboratories. It describes two main approaches provided by the NORDTEST handbook: 1) combining reproducibility within the laboratory and estimates of method and laboratory bias, and 2) using reproducibility between laboratories. It then provides detailed guidance on estimating various components of uncertainty, including reproducibility within the laboratory using control samples, accounting for different matrices and concentration levels, and estimating bias using reference materials and proficiency testing. Flowcharts and examples are provided to illustrate the processes.
What is a measurement and what measurement is not
What is uncertainty of measurement?
Error versus uncertainty
Why is uncertainty of measurement important?
Basic statistics on sets of numbers
The general kinds of uncertainty in any measurement
For a free course, visit - www.theapprentiice.com
The laboratory shall determine measurement uncertainty for each measurement procedure,
in the examination phases used to report measured quantity values on patients’ samples. The
laboratory shall define the performance requirements for the measurement uncertainty of each
measurement procedure and regularly review estimates of measurement uncertainty.
What is a measurement and what measurement is not
What is uncertainty of measurement?
Error versus uncertainty
Why is uncertainty of measurement important?
Basic statistics on sets of numbers
The general kinds of uncertainty in any measurement
For a free course, visit - www.theapprentiice.com
The laboratory shall determine measurement uncertainty for each measurement procedure,
in the examination phases used to report measured quantity values on patients’ samples. The
laboratory shall define the performance requirements for the measurement uncertainty of each
measurement procedure and regularly review estimates of measurement uncertainty.
Principles and Practices of Traceability and CalibrationJasmin NUHIC
To learn and understand different types of measurements units, measurement constants, calibration and measurement standards as well as principles and practices of treaceability.
Common mistakes in measurement uncertainty calculationsGH Yeoh
The basic calculation for measurement uncertainty (MU) is through the law of propagation of uncertainty. Some find it difficult to apply and make some mistakes in the MU evaluation.
The requirements of reliability and accuracy of a test result cannot be over emphasized. Having a robust QA/QC system in place ensures the client's confidence in accepting your certificate of analysis.
The objective of any chemical analytical measurement is to get consistent, reliable and accurate data.
Proper functioning and performance of analytical instruments and computer systems plays a major role in achieving this goal.
Therefore, analytical instrument qualification (AIQ) and calibration should be part of any good analytical practice.
Principles and Practices of Traceability and CalibrationJasmin NUHIC
To learn and understand different types of measurements units, measurement constants, calibration and measurement standards as well as principles and practices of treaceability.
Common mistakes in measurement uncertainty calculationsGH Yeoh
The basic calculation for measurement uncertainty (MU) is through the law of propagation of uncertainty. Some find it difficult to apply and make some mistakes in the MU evaluation.
The requirements of reliability and accuracy of a test result cannot be over emphasized. Having a robust QA/QC system in place ensures the client's confidence in accepting your certificate of analysis.
The objective of any chemical analytical measurement is to get consistent, reliable and accurate data.
Proper functioning and performance of analytical instruments and computer systems plays a major role in achieving this goal.
Therefore, analytical instrument qualification (AIQ) and calibration should be part of any good analytical practice.
Measurement errors, Statistical Analysis, UncertaintyDr Naim R Kidwai
The Presentation covers Measurement Errors and types, Gross error, systematic error, absolute error and relative error, accuracy, precision, resolution and significant figures, Measurement error combination, basics of statistical analysis, uncertainty, Gaussian Curve, Meaning of Ranges
Please refer this file just as reference material. More concentration should on class room work and text book methodology.
Introduction to Mechanical Measurement
Statistics is the science of dealing with numbers.
It is used for collection, summarization, presentation and analysis of data.
Statistics provides a way of organizing data to get information on a wider and more formal (objective) basis than relying on personal experience (subjective).
Statistical methods and analyses are used to communicate research findings and give credibility to research methodology and conclusions. It is important for researchers and also consumers of research to understand statistics so that they can be informed, evaluate the credibility and usefulness of information, and make appropriate decisions.
Analytical Method Validation is a process that is used to demonstrate the suitability of an analytical method for an intended purpose.Regulations and quality standards that have an impact on analytical laboratories require analytical methods to be validated.
Variability of clinical chemistry laboratory resultsAdetokunboAjala
Understanding the concepts associated with variability of laboratory results would help laboratorians improve the quality of laboratory service as well as aid the drive towards harmonization of laboratory quality practices.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Phone Us ❤85270-49040❤ #ℂall #gIRLS In Surat By Surat @ℂall @Girls Hotel With...
Measurement uncertainty
1. Annex 58
Universität Stuttgart
Measurement Uncertainty
Dr.-Ing. Michael Koch
Institute for Sanitary Engineering, Water Quality and Solid
Waste Management, Universität Stuttgart
Dep. Hydrochemistry
Bandtäle 2, 70569 Stuttgart
Tel.: +49 711/685-5444 Fax: +49 711/685-7809
E-mail: Michael.Koch@iswa.uni-stuttgart.de
http://www.uni-stuttgart.de/siwa/ch
Practical approach for the estimation of
measurement uncertainty
NORDTEST: Handbook for calculation of
measurement uncertainty in
environmental laboratories
available from: www.nordtest.org
(technical report 537)
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
2. NORDTEST-approach - 2 possibilities
a) combination of
Reproducibility within the laboratory and
Estimation of the method and laboratory
bias
b) Use of reproducibility between
laboratories more or less directly
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Customer needs
Before calculating or estimating the
measurement uncertainty, it is recommended
to find out what are the needs of the
customers
The main aim of the actual uncertainty
calculations will be to find out if the
laboratory can fulfil the customer demands
Customers are not used to specifying
demands, so in many cases the demands
have to be set in dialogue with the customer.
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
3. Flowchart for Method a)
Specify measurand
Quantify components for within lab reproducibility
A control samples
B possible steps, not covered by the control sample
Quantify bias components
Convert components to standard uncertainty
u1 u1 + u2
Calculate combined standard uncertainty
u2
Calculate expanded uncertainty U = 2 ⋅ uc
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Reproducibility within the laboratory Rw
Control sample covering the whole analytical process
if
the control sample covers the whole analytical process and
has a matrix similar to the samples,
the within-laboratory reproducibility at that concentration level
can simply be estimated from the analyses of the control sample
If the analyses performed cover a wide range of concentration
levels, also control samples of other concentration levels should
be used.
value rel. Uncertainty Comments
Reproducibility within the lab Rw
control sample 1 sRw standard deviation 2.5 % from 75 measure-
X = 20.01 µg/l 0.5 µg/l ments in 2002
control sample 1 sRw standard deviation 1.5 % from 50 measure-
X = 250.3 µg/l 3.7 µg/l ments in 2002
other components ---
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
4. Reproducibility within the laboratory Rw
Control samples for different matrices and concentrations
if
a synthetic control solution is used for quality control, and
the matrix type of the control sample is not similar to the natural
samples
we have to take into consideration uncertainties arising from
different matrices
These can be estimated from the repeatability with different
matrices (range control chart)
value u(x) Comments
Reproducibility within the lab Rw
low level sRw 0.5 µg/l from the mean control chart 0.6 µg/l Absolute:
(2-15 µg/l) 0.37 µg/l from the range control chart u( x ) = 0.5 2 + 0.37 2
high level sRw 1.5 % from the mean control chart 3.9 % Relative:
(>15 µg/l) 3.6 % from the range control chart u ( x ) = 1 .5 % 2 + 3 .6 % 2
Note: The repeatability component is included two times!!
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Reproducibility within the laboratory Rw
Unstable control samples
if
the laboratory does not have access to stable control samples (e.g.
measurement of dissolved oxygen)
it is possible only to estimate uncertainty components from
repeatibility via the range control chart
the „long-term“ uncertainty component (from batch to batch) has
to be estimated e.g. by a qualified guess
value u(x) Comments
Reproducibility within the laboratory Rw
Duplicate measurements of natural sr s = 0.024 mg/l 0.32 % from 50
samples mean: 7.53 mg/l measurements
Estimated variation from differences in s = 0.5 % 0.5 % based on
calibration over time experience
Combined uncertainty for Rw
0.32%2 + 0.5%2 = 0.59%
Repeatability + Reproducibility in
calibration
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
5. Method and Laboratory bias
can be estimated from
the analysis of certified reference materials
the participation in proficiency tests
from recovery experiments
Sources of bias should always be eliminated if
possible
According to GUM a measurement result should
always be corrected if the bias is significant and
based on reliable data such as a CRM.
In many cases the bias can vary depending on
changes in matrix. This can be reflected when
analysing several matrix CRMs
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Method and Laboratory bias u(bias)
Components of uncertainty
the bias (as % difference from the nominal or
certified value)
the uncertainty of the nominal/certified value u(Cref)
u(bias) can be estimated by:
u(bias ) = RMSbias + u(Cref )2
2
with RMSbias =
∑ (bias ) i
2
n
and if only one CRM is used
2
s
u(bias ) = (bias )2 + bias + u(Cref )2
n
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
6. Method and Laboratory bias u(bias)
Use of one certified reference material
The reference material should be analysed in at least
5 different analytical series
Example: Certified value: 11.5 ± 0.5 (95% confidence
interval)
Uncertainty component from the uncertainty of the certified
value
Convert the confidence The confidence interval is ± 0.5. Divide this
interval by 1.96 to convert it to standard
uncertainty: 0.5/1.96=0.26
Convert to relative uncertainty u(Cref) 100⋅(0.26/11.5)=2.21%
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Method and Laboratory bias u(bias)
Use of one certified reference material
Quantify the bias
the CRM was analysed 12 times. The mean is 11.9 with a
standard deviation of 2.2%
This results in:
bias = 100 ⋅ (11.9 − 11.5) / 11.5 = 3.48% and
sbias = 2.2% with n = 12
Therefore the standard uncertainty is:
2
s
u(bias ) = (bias )2 + bias + u(Cref )2 =
n
2
2.2%
(3.48%)2 + + 2.21%2 = 4.2%
12
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
7. Method and Laboratory bias u(bias)
Use of several certified reference material
Quantification of the bias
bias CRM1 is 3.48%, s=2.2% (n=12), u(Cref)=2.21%
bias CRM2 is –0.9%, s=2.0% (n=7), u(Cref)=1.8%
bias CRM3 is 2.4%, s=2.8% (n=10), u(Cref)=1.8%
RMSbias then is:
RMSbias =
∑ (bias ) i
2
=
3.48%2 + ( −0.9%)2 + 2.4%2
= 2 .5 %
n 3
and the mean uncertainty of the certified value u(Cref): 1.9%
This results in the total standard uncertainty of the bias:
u(bias ) = RMSbias + u(Cref )2 = 2.5%2 + 1.9%2 = 3.1%
2
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Method and Laboratory bias u(bias)
Use of PT results
In order to have a reasonably clear picture of
the bias from interlaboratory comparison results,
a laboratory should participate at least 6 times
within a reasonable time interval
Uncertainty component from the uncertainty of the nominal
value
between laboratory sR has been on average 9% in the 6
standard deviations sR exercises
Convert to relative uncertainty u(Cref) Mean number of participants= 12
s 9%
u(Cref ) = R = = 2.6%
n 12
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
8. Method and Laboratory bias u(bias)
Use of PT results
Quantification of the bias
In the 6 participations the biases have been:
2%, 7%, -2%, 3%, 6% and 5%
Therefore RMSbias is:
RMSbias =
∑ (bias ) i
2
=
2%2 + 7%2 + ( −2%)2 + 3%2 + 6%2 + 5%2
= 4 .6 %
n 7
and the total standard uncertainty of the bias:
u(bias ) = RMSbias + u(Cref )2 = 4.6%2 + 2.6%2 = 5.3%
2
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Method and Laboratory bias u(bias)
From Recovery Tests
Recovery tests, for example the recovery of a standard addition to a
sample in the validation process, can be used to estimate the
systematic error. In this way, validation data can provide a valuable
input to the estimation of the uncertainty.
Example: In an experiment the recoveries for an added spike were
95 %, 98 %, 97 %, 96 %, 99 % and 96 % for 6 different sample
matrices. The spike of 0.5 mL was added with a micropipette.
uncertainty component from spiking
uncertainty of the concentration of the spike from the certificate:
u(conc) 95% confidence intervall = ± 1.2 %
u(conc) = 0.6 %
uncertainty of the added volume u(vol) from the manufacturer of the micro pipette:
max. bias: 1% (rectangular interval),
repeatability: max. 0.5% (standard dev.)
2
1%
u(vol ) = + 0.5%2 = 0.76%
3
uncertainty of the spike u(crecovery) u(conc )2 + u(vol )2 = 0.6%2 + 0.76%2 = 1.0%
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
9. Method and Laboratory bias u(bias)
From Recovery Tests
Quantification of the bias:
RMSbias:
5% 2 + 2% 2 + 3 % 2 + 4% 2 + 1 % 2 + 4% 2
RMSbias = = 3.44%
6
Therefore the total standard uncertainty of the bias is:
u(bias ) = RMSbias + u(Cre cov ery )2 = 3.44%2 + 1.0%2 = 3.6%
2
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Combination of the uncertainties
(Reproducibility within the laboratory and bias)
Reproducibility (Rw) (from control
samples and other estimations)
bias u(bias) (from CRM, PT or recovery
tests)
Combination:
uc = u(Rw )2 + u(bias )2
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
10. Calculation of the expanded uncertainty
for the conversion to a 95% confidence
level
U = 2 ⋅ uc
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Method b) - direct use of reproducibility
standard deviations
If the demand on uncertainty is low
u c = sR
the expanded uncertainty becomes U = 2 ⋅ SR
This may be an overestimate depending on
the quality of the laboratory – worst-case
scenario
It may also be an underestimate due to
sample inhomogeneity or matrix variations
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
11. Reproducibility standard deviation from a
standard
The laboratory must first prove that they are
able to perform in accordance with the
standard method
„no“ bias
verification of the repeatability
The expanded uncertainty then is:
U = 2 ⋅ sR
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Reproducibility standard deviation from a standard
Example – Mercury according to EN 1483
reproducibility variation coefficient
drinking water
surface water
waste water
Expanded uncertainty for drinking
water:
U = 2⋅VCR ≈ 60 %
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
12. Reproducibility standard deviation from a
PT
The laboratory must have been successfully
participating in the PT
If the comparison covers all relevant
uncertainty components and steps (matrix?)
The expanded uncertainty then also is:
U = 2 ⋅ sR
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Reproducibility standard deviation from a PT
Example – Mercury in a Univ. Stuttgart PT
uc = sR ≈ 20%
rob. Standardabweichung [µg/l]
Ausschlussgrenze unten [µg/l]
Ausschlussgrenze oben [µg/l]
rel. Standardabweichung [%]
Ausschlussgrenze unten [%]
Ausschlussgrenze oben [%]
reproducibility variation coefficient U ≈ 40%
außerhalb unten
außerhalb oben
Vorgabe [µg/l]
außerhalb [%]
Anzahl Werte
Niveau
1 0,584 0,1334 22,86 0,889 0,341 52,25 -41,60 37 3 1 10,8
2 1,248 0,2256 18,09 1,748 0,830 40,07 -33,46 39 3 1 10,3
3 1,982 0,3502 17,67 2,756 1,333 39,06 -32,75 39 1 0 2,6
4 3,238 0,4726 14,60 4,263 2,352 31,65 -27,36 41 2 2 9,8
5 3,822 0,4550 11,90 4,793 2,960 25,40 -22,55 38 0 1 2,6
6 4,355 0,7704 17,69 6,057 2,927 39,10 -32,78 40 1 0 2,5
7 5,421 0,7712 14,23 7,090 3,973 30,78 -26,71 41 1 1 4,9
8 6,360 0,7361 11,57 7,928 4,963 24,65 -21,96 38 5 1 15,8
9 6,553 0,9177 14,00 8,536 4,829 30,25 -26,31 39 2 0 5,1
10 7,361 0,9965 13,54 9,508 5,486 29,16 -25,48 40 1 3 10,0
11 8,063 1,0672 13,24 10,357 6,051 28,46 -24,94 38 5 2 18,4
12 9,359 0,9854 10,53 11,444 7,481 22,29 -20,06 40 2 2 10,0
Summe 470 26 14 8,5
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
13. Summary
Two different methods to estimate the measurement
uncertainty have been introduced:
Method a)
Estimation of the within-lab reproducibility (mainly from
control charts)
Estimation of the bias (from analyses of CRM, PT results or
recovery tests)
Combination of both components
Method b)
direct use of the reproducibility standard deviation from
standards or PTs as combined standard uncertainty
As a rule method b) delivers higher measurement
uncertainties (conservative estimation)
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart
Bibliography
ISO: "Guide to the expression of uncertainty in measurement" (ISBN 92-
67-10188-9)
EURACHEM/CITAC: Quantifying Uncertainty in Analytical Measurement,
2nd Edition (2000) (www.eurachem.ul.pt)
NORDTEST: Handbook for calculation of measurement uncertainty in
environmental laboratories. Report TR 537 (www.nordtest.org)
LGC/VAM: Development and Harmonisation of Measurement Uncertainty
Principles Part(d): Protocol for uncertainty evaluation from validation data
(www.vam.org.uk)
Niemelä, S.I.: Uncertainty of quantitative determinations derived by
cultivation of microorganisms. MIKES-Publication J4/2003 (www.mikes.fi)
EA Guidelines on the Expression of Uncertainty in Quantitative Testing
EA-4/16 (rev.00) 2003 (www.european-accreditation.org)
ILAC-G17:2002 Introducing the Concept of Uncertainty of Measurement
in Testing in Association with the Application of the Standard ISO/IEC
17025 (www.ilac.org)
A2LA: Guide for the Estimation of Measurement Uncertainty In Testing"
2002 (www.a2la2.net)
Institute for Sanitary Engineering, Water Quality and Solid Waste Management, Universität Stuttgart