The Joint Committee for Guides in Metrology, Working Group 1, JCGM-WG1, is currently revising the 'Guide to the Expression of Uncertainty in Measurement'. In this communication, the motivation for undertaking such a revision is given and the main changes with respect to the current, 2008 edition are outlined.

Vulnerable travellers experience various problems in the transport environment. These may reduce public travel confidence and consequently lead to decreased mobility. A goal of our research is to find out how to improve the accessibility to railway travelling, especially, for persons with functional limitations. By reducing barriers, the ability of travelling would be improved, and consequently allow for more flexible travel behaviors. In order to develop a model and a method of measurement for accessibility, we (a) constructed a reference group of representative ‘typical older persons’ (65-85 years) from questionnaire data, and (b) developed an accessibility measure for persons with functional limitations. In this measure barriers have different weights for the different persons depending on their functional ability and travel behavior. This gives the probability of facing a certain barrier when travelling to a certain destination; that is, a measure of accessibility for the individual. The more weight placed on a certain barrier, the less probable it is that the particular journey will take place. These weights will be obtained in forthcoming research on the perception of a set of various travel scenarios representing barriers.

Valid and precise quantification of clinical variables is essential for appropriate interpretation to inform healthcare decision making. The outcomes produced from different measurement procedures and instruments, purporting to quantify the same measurand, should be directly comparable. This ensures the appropriate application and widespread adoption of clinical research findings. Metrology provides a framework for the development of a common language of reference measurement systems, which have the potential to improve the accuracy and comparability of patients’ results. However, the practices, procedures and instruments used in social measurement are currently excluded from any formal metrological framework. In this paper, we build on previous arguments, and propose a new international body to bring together metrology, psychometrics, philosophy, and clinical management to support the global comparability and equivalence of measurement results in patient centred outcome measurement to improve healthcare.

Patient centered outcomes pertain to a patient's beliefs, opinions and needs in conjunction with a clinician's medical expertise and assessment. The rise of patient-centered outcome (PCO) measurement parallels increased interest in patient-centered care. PCO measures offer the opportunity for more meaningful measurement of health outcomes informative enough to guide treatment decisions. However, it has been suggested that, for practical and scientific reasons, existing PCO measures are currently not capable of delivering the kind of quality assured measurement required for high-stakes decision making. Potential solutions include: addressing the lack of units in PCO measurement through recourse to mathematical models devised to define meaningful, invariant, and additive units of measurement with known uncertainties; establishing coordinated international networks of key stakeholders guided by five principles (i.e., collaboration, alignment, integration, innovation and communication); better use of technology leveraging measurement through item banks linking PCO reports via common items, common patients, or specification equations based in strong explanatory theory. And finally ensuring PCO measurement always is associated with: (1) a clear definition of the measurand in regards to the intended clinical use; (2) a clear definition of the clinically allowable error of measurement; (3) international cooperation and consensus to navigate the complexities of the development of metrologically sound reference measurement systems; and (4) continued clinical validation of newly calibrated measures. In this article, we illustrate the principles to improve PCO measures with examples from breast cancer, vision-related patient-reported outcome measures, and dementia clinician-reported and performance outcome measures.

This paper presents a case study of more effective decision rules for the conformance assessment of electrical energy meters in private households in Norway, and proposes how to use a specific risk analysis in order to set the time for the next meter test. The MID regulation today prescribes conformance assessment of electrical energy meters based on ISO standards for attribute sampling where decision rules are purely statistical decision rules and economic consequences are not explicitly taken into account. The risk analysis we introduce calculates the risks involved for erroneous decisions, either rejecting a conforming batch of meters (the producer risk) or accepting a non-conforming batch (the consumer risk). The consumer risk is sensitive to the period until the next test which becomes a quality characteristic of each batch. This time interval can be optimized by balancing the consumer risk against the producer risk. When the quality drops, the period until the next test will need to become shorter. But at a certain level of quality, the energy net supplier would rather replace the complete batch, than continue testing at such short intervals.

Why metrology? What special value does it offer to the design and use of sustainability impact metrics, and so to the realization of the United Nations Sustainable Development Goals? One answer in short, is, "For justice." The balance scale is a universal symbol of fairness, development and equality. A second brief reply is, "For efficient markets." Common currencies for the exchange of value are well known as a key factor in lowering transaction costs and supporting property rights, both essential to market formation. The repeatedly encountered dilemma, of course, is how to design, calibrate, and use measures of economic, environmental, human, and social value that lower costs and are just in more than name alone, serving some but not others. Longer answers justify metrological traceability to consensus unit standards as a key factor in realizing the SDGs by showing how it contributes to (a) the cultivation of shared meanings and improved communication; (b) the grounding of pragmatic expressions of verified trust; (c) making real, reproducible developmental trajectories visible and manageable; and (d) creating the multilevel systems of systems required for managing and governing complex, adaptive, self-organizing forms of social, political, legislative and economic life. A more complete answer to the question, "Why metrology?," then focuses on how the SDGs' diverse stakeholder interests may be most effectively fulfilled via collective actions facilitated on the basis of shared values.

The 12th comparison between the Swedish National Platinum-Iridium kilogram (Proto¬type number 40) and the principal kilogram standards for mass has been performed at SP Swedish National Testing and Research Institute. The method used was a weighted least square method with restraint developed by Dr Leslie Pendrill < >. Weighings for the pan-European key intercomparisons for 1 kg, EUROMET 509 and 510 were made together with the regular kilogram comparison.

Magnetic forces can adversely affect weighings since, without systematic investigation, these spurious forces cannot be distinguished from the gravitational forces to be compared in the determination of mass. Magnetic forces can result from the mutual interaction of two mass standards as well as between a mass standard and the mass comparator being used for the weighing. Magnetic forces arise in the influence of a magnetic field gradient on a mass standard possessing a magnetic dipole moment; the latter may either exist permanently or may be induced by the applied magnetic field. This report summarises the effects of magnetism in weighing and methods developed to determine the magnetic properties of mass standard and comparator.

PURPOSE: The purpose of this study was to develop and test a new method to measure the usability of absorbent incontinence care products from the caregivers' perspective and to investigate if the method can be used to differentiate between product types in a product change.

DESIGN: Process evaluation and validation study.

SUBJECTS AND SETTING: Product developers and end users participated in designing the new method. Thereafter, professional caregivers acted as testers of the new method, ranking usability when performing absorbent product changes on patients in a simulated nursing home care environment, assisted by third-party research institute moderators.

METHODS: Design and evaluation of a new method designed to assess the usability of body-worn absorbent incontinence care products for lay caregivers were completed. The evaluation included formative and summative evaluations of effectiveness (product fit), efficiency (time and physical workload), and satisfaction. A person-centered approach aimed at including all subjects and settings to generate a single usability score for decision making and product benchmarking. Experienced caregivers changed 4 types of products: (1) disposable body-worn pads with mesh briefs (2-piece system); (2) disposable all-in-one briefs; (3) disposable, T-shaped, and belted brief; and (4) disposable pull-up pants on simulated patients in standing or lying position. Each product change was performed by 1 unassisted experienced caregiver. The probability of success as a score for each product type was calculated across the 4 metrics and reported with 95% confidence intervals (CIs). Descriptive and inferential statistics were developed assuming a binary statistical model, using the weighted scores from each of the factors. An overall usability score was calculated.

RESULTS: The method we developed discriminated between usability of different product types. The overall score for the disposable pull-up product (90%; CI: 83%-97%) was better (P < .05) than for the disposable T-shaped brief (83%; CI: 77%-89%), the disposable brief (53%; CI: 45%-61%), and the disposable body-worn pad with mesh pant (61%; CI: 56%-66%) in standing patients. For lying patients, the overall score for the disposable T-shaped brief product (81%; CI: 73%-89% was better (P < .05) than the disposable brief (65%; CI: 45%-61%) and the disposable body-worn pads with mesh brief (62%; CI: 55%-69%). Reliability was evaluated quantitatively in terms of measurement uncertainties in the results.

CONCLUSION: The method we described demonstrated differentiation of usability based on product type indicating concurrent validity. Further testing in diverse real-world care environments is needed to evaluate and confirm the validity and to assess reliability of this method in the research setting.

Measurement units have historically been defined as quantities (i.e., specific properties) of objects, such as the mass of a particular piece of metal or the length of a particular rod. While the current International System of Units (SI) Brochure endorses this position, the draft 9th SI Brochure proposes to change it, and instead define measurement units as values of quantities. The reason for this proposed change is not provided, but it does not seem plausible that it is related to the redefinition of the SI units in terms of fundamental constants of nature: the very concept of what a unit is does not depend on the concrete way any given unit is defined. This paper is intended to open a discussion of whether measurement units should be defined as quantities or as quantity values, and provides our rationale for maintaining the definition of units as quantities.

BACKGROUND: Mobile health (mHealth) apps offer great opportunities to deliver large-scale, cost-efficient digital solutions for implementing lifestyle changes. Furthermore, many mHealth apps act as medical devices. Yet, there is little research on how to assess user satisfaction with an mHealth solution. OBJECTIVE: This study presents the development of the mHealth Satisfaction Questionnaire and evaluates its measurement properties. METHODS: Respondents who took part in the Health Integrator Study and were randomized to use the Health Integrator smartphone app for lifestyle changes (n=112), with and without additional telephone coaching, rated their satisfaction with the app using the new 14-item mHealth Satisfaction Questionnaire. The ratings were given on a 5-point Likert scale and measurement properties were evaluated using Rasch measurement theory (RMT). RESULTS: Optimal scoring was reached when response options 2, 3, and 4 were collapsed, giving three response categories. After omitting two items that did not fit into the scale, fit residuals were within, or close to, the recommended range of ±2.5. There was no differential item functioning between intervention group, age group, or sex. The Person Separation Index was 0.79, indicating that the scale's ability to discriminate correctly between person leniency was acceptable for group comparisons but not for individual evaluations. The scale did not meet the criterion of unidimensionality; 16.1% (18/112) of the respondents were outside the desired range of -1.96 to 1.96. In addition, several items showed local dependency and three underlying dimensions emerged: negative experiences, positive experiences, and lifestyle consequences of using the mHealth solution. CONCLUSIONS: In times where mHealth apps and digital solutions are given more attention, the mHealth Satisfaction Questionnaire provides a new possibility to measure user satisfaction to ensure usability and improve development of new apps. Our study is one of only a few cases where RMT has been used to evaluate the usability of such an instrument. There is, though, a need for further development of the mHealth Satisfaction Questionnaire, including the addition of more items and consideration of further response options. The mHealth Satisfaction Questionnaire should also be evaluated in a larger sample and with other mHealth apps and in other contexts. TRIAL REGISTRATION: ClinicalTrials.gov NCT03579342; http://clinicaltrials.gov/ct2/show/NCT03579342. ©Jeanette Melin, Stephanie Erika Bonn, Leslie Pendrill, Ylva Trolle Lagerros. Originally published in JMIR mHealth and uHealth (http://mhealth.jmir.org), 26.05.2020.

Construct specification equations (CSEs), providing a comprehensive understanding of the construct purported to be measured and how a collection of items works together causally, are candidate ‘recipes for certified reference materials’ (CRM). Analogous to the role of CRMs in areas such as chemistry and material properties, CSEs appear to provide metrological traceability in the human sciences. In this work we illustrate how memory test items, Rasch Measurement Theory (RMT) and CSEs can be brought together to help ‘tell a clearer story’ about memory decline that links language- and cultural-free items (blocks, digits) to more complex word recall. Combining different test items to form novel cognitive metrics, done carefully so not jeopardize validity and to enhance coherence in item design and purpose, is guided by entropy-based equivalence criteria identified in the CSEs. The novel NeuroMET Memory Metric may enable better-informed high stakes decision-making and more efficient and valid cognitive assessment.

Better metrics of cognition can be formed by carefully combining selected items from legacy short-term memory tests so as to enhance coherence in item design while not jeopardizing validity. In this paper, we report on how Rasch Measurement Theory and Construct specification equations (CSE) have been brought together when composing the NeuroMET Memory Metric (NMM). The NMM is guided by: i) entropy-based equivalence criteria; ii) a comprehensive understanding of the construct purported to be measured; and iii) how a collection of items works together. CSEs play a major role in ensuring the metrological legitimacy of the NMM in a way analogous to certified reference materials in more established areas of metrology. The resulting NMM for short-term memory recall has up to a five-fold reduction in measurement uncertainties for memory ability compared with an individual legacy test, and the entropy-based CSEs should enable more efficient and valid assessment. © 2022 The Authors

Accurate assessment of memory ability for persons on the continuum of Alzheimer’s disease (AD) is vital for early diagnosis, monitoring of disease progression and evaluation of new therapies. However, currently available neuropsychological tests suffer from a lack of standardization and metrological quality assurance. Improved metrics of memory can be created by carefully combining selected items from legacy short-term memory tests, whilst at the same time retaining validity, and reducing patient burden. In psychometrics, this is known as “crosswalks” to link items empirically. The aim of this paper is to link items from different types of memory tests. Memory test data were collected from the European EMPIR NeuroMET and the SmartAge studies recruited at Charité Hospital (Healthy controls n = 92; Subjective cognitive decline n = 160; Mild cognitive impairment n = 50; and AD n = 58; age range 55–87). A bank of items (n = 57) was developed based on legacy short-term memory items (i.e., Corsi Block Test, Digit Span Test, Rey’s Auditory Verbal Learning Test, Word Learning Lists from the CERAD test battery and Mini Mental State Examination; MMSE). The NeuroMET Memory Metric (NMM) is a composite metric that comprises 57 dichotomous items (right/wrong). We previously reported on a preliminary item bank to assess memory based on immediate recall, and have now demonstrated direct comparability of measurements generated from the different legacy tests. We created crosswalks between the NMM and the legacy tests and between the NMM and the full MMSE using Rasch analysis (RUMM2030) and produced two conversion tables. Measurement uncertainties for estimates of person memory ability with the NMM across the full span were smaller than all individual legacy tests, which demonstrates the added value of the NMM. Comparisons with one (MMSE) of the legacy tests showed however higher measurement uncertainties of the NMM for people with a very low memory ability (raw score ≤ 19). The conversion tables developed through crosswalks in this paper provide clinicians and researchers with a practical tool to: (i) compensate for ordinality in raw scores, (ii) ensure traceability to make reliable and valid comparisons when measuring person ability, and (iii) enable comparability between test results from different legacy tests. © 2023, The Author(s).

To ensure reliable diagnosis and treatment consistently throughout healthcare, metrological quality assurance is essential. There are, however, many observations in the social sciences and healthcare, such as the memory tests studied here, which have been ‘claimed’ to be measurements but in fact have not been fully metrologically legitimated. We have already argued in favour of extending traditional metrological underlying principles to cover social measurements, including the development of construct specification equations (CSE) considered as ‘recipes for certified reference materials (CRM)’ for traceability, analogous to CRMs in metrology in chemistry. Although the CSE approach has to date been used mostly to explain and validate test item attributes, this paper turns to focus on causal explanations of person characteristics. We describe methods and preliminary results developed in the European EMPIR NeuroMET projects, which may be used for providing quality assured measurement of disease progression and treatment benefits for patients with neurodegenerative conditions. 

Metrological methods for word learning list tests can be developed with an information theoretical approach extending earlier simple syntax studies. A classic Brillouin entropy expression is applied to the analysis of the Rey’s Auditory Verbal Learning Test RAVLT (immediate recall), where more ordered tasks—with less entropy—are easier to perform. The findings from three case studies are described, including 225 assessments of the NeuroMET2 cohort of persons spanning a cognitive spectrum from healthy older adults to patients with dementia. In the first study, ordinality in the raw scores is compensated for, and item and person attributes are separated with the Rasch model. In the second, the RAVLT IR task difficulty, including serial position effects (SPE), particularly Primacy and Recency, is adequately explained (Pearson’s correlation = 0.80) with construct specification equations (CSE). The third study suggests multidimensionality is introduced by SPE, as revealed through goodness-of-fit statistics of the Rasch analyses. Loading factors common to two kinds of principal component analyses (PCA) for CSE formulation and goodness-of-fit logistic regressions are identified. More consistent ways of defining and analysing memory task difficulties, including SPE, can maintain the unique metrological properties of the Rasch model and improve the estimates and understanding of a person’s memory abilities on the path towards better-targeted and more fit-for-purpose diagnostics. © 2022 by the authors. 

Background: The ability to measure, track over time, and compare memory ability for people with neurodegeneration is important. However, currently, full comparability of memory test data is limited by a lack of quality assurance of memory measurements. At AAIC 2021, we presented a preliminary item bank to assess memory, composed by selecting items from legacy tests according to metrological principles through use of the Rasch model and with item equivalence based on entropy. Method: Here, we demonstrate direct comparability of measurements generated from different tests, with the new NeuroMET Memory Metric comprising 87 selected items for task difficulty from: the Corsi Block Test, Digit Span Test, Rey’s Auditory Verbal Learning Test, Word Learning List from the CERAD test battery and the Mini Mental State Examination. Data were collected from the European EMPIR NeuroMET and the SmartAge studies recruited at Charité Hospital (Healthy controls n = 92; Subjective cognitive decline n = 160; Mild Cognitive Impairment n = 50; and Alzheimer’s Disease n = 58; age range 55-87). Results: The Rasch analysis showed well-targeted items for all participants’ abilities; good fit to the measurement model, with 83 items (95%) having fit residuals within the expected range and satisfactory unidimensionality, and item reliability of 0.96. The full item bank comprising 87 short-term memory items gave a person reliability of 0.85. Subsequently, a conversion table was created linking the raw scores from the legacy tests to the common NeuroMET Memory Metric and to individual legacy tests. Conclusion: Legacy memory tests have previously proven useful in clinical practice and research, and will continue to be used, but have to date been metrologically limited. The provided conversion table, linking these legacy memory tests to a metrologically assured scale, viz., the NeuroMET memory metric, remedies this deficiency. The NeuroMET memory metric will be included in the first ever prototype of a metrological validated app used to deliver memory tests. Clinicians and researchers will be able to select sets of items to produce data, via a scoring algorithm for transforming patient responses to measures, in a common frame of reference.

Commonly used rating scales and tests have been found lacking reliability and validity, for example in neurodegenerative diseases studies, owing to not making recourse to the inherent ordinality of human responses, nor acknowledging the separability of person ability and item difficulty parameters according to the well-known Rasch model. Here, we adopt an information theory approach, particularly extending deployment of the classic Brillouin entropy expression when explaining the difficulty of recalling non-verbal sequences in memory tests (i.e., Corsi Block Test and Digit Span Test): a more ordered task, of less entropy, will generally be easier to perform. Construct specification equations (CSEs) as a part of a methodological development, with entropy-based variables dominating, are found experimentally to explain (r =√R2 = 0.98) and predict the construct of task difficulty for short-term memory tests using data from the NeuroMET (n = 88) and Gothenburg MCI (n = 257) studies. We propose entropy-based equivalence criteria, whereby different tasks (in the form of items) from different tests can be combined, enabling new memory tests to be formed by choosing a bespoke selection of items, leading to more efficient testing, improved reliability (reduced uncertainties) and validity. This provides opportunities for more practical and accurate measurement in clinical practice, research and trials. © 2021 by the authors.

Objective: To evaluate the Patient Participation in Rehabilitation Questionnaire (PPRQ) according to Rasch measurement theory. Method: Five hundred twenty-two post-discharge patients from a neurological rehabilitation unit were included. The PPRQ questionnaire comprises 20 items rated by a cohort of 522 patients about their experiences of participating in rehabilitation. The measurement properties of the PPRQ were evaluated by Rasch analysis of the responses. Results: The Rasch analysis of 20 items showed some major misfits, particularly three items addressing the involvement of family members. After removing those items, the model fit improved and no significant DIF remained. Despite improvements, person values (−2.96 to 4.86 logits) were not fully matched by the item values (−0.61 to 0.77 logits). Neither did the t test for unidimensionality meet the criterion of 5%, and local dependency was present. The unidimensionality and local dependency could, however, be accommodated for by four testlets. Conclusion: The PPRQ-17 showed that a ruler with a reasonable and clinical hierarchy can be constructed, although the expectations of dimensionality and local dependency need to be evaluated further. Despite room for further development, PPRQ-17 nevertheless shows improved measurement precision in terms of patient leniency compared with previous evaluations with classical test theory. In turn, this can play a crucial role when comparing different rehabilitation programs and planning tailored care development activities.

Both construct specification equations (CSEs) and entropy can be used to provide a specific, causal, and rigorously mathematical conceptualization of item attributes in order to provide fit-for-purpose measurements of person abilities. This has been previously demonstrated for memory measurements. It can also be reasonably expected to be applicable to other kinds of measures of human abilities and task difficulty in health care, but further exploration is needed about how to incorporate qualitative explanatory variables in the CSE formulation. In this paper we report two case studies exploring the possibilities of advancing CSE and entropy to include human functional balance measurements. In case study I, physiotherapists have formulated a CSE for balance task difficulty by principal component regression of empirical balance task difficulty values from Berg’s Balance Scale transformed using the Rasch model. In case study II, four balance tasks of increasing difficulty due to diminishing bases of support and vision were briefly investigated in relation to entropy as a measure of the amount of information and order as well as physical thermodynamics. The pilot study has explored both methodological and conceptual possibilities and concerns to be considered in further work. The results should not be considered as fully comprehensive or absolute, but rather open up for further discussion and investigations to advance measurements of person balance ability in clinical practice, research, and trials. © 2023 by the authors.

There are different views in the literature about the number and inter-relationships of cognitive domains (such as memory and executive function) and a lack of understanding of the cognitive processes underlying these domains. In previous publications, we demonstrated a methodology for formulating and testing cognitive constructs for visuo-spatial and verbal recall tasks, particularly for working memory task difficulty where entropy is found to play a major role. In the present paper, we applied those insights to a new set of such memory tasks, namely, backward recalling block tapping and digit sequences. Once again, we saw clear and strong entropy-based construct specification equations (CSEs) for task difficulty. In fact, the entropy contributions in the CSEs for the different tasks were of similar magnitudes (within the measurement uncertainties), which may indicate a shared factor in what is being measured with both forward and backward sequences, as well as visuo-spatial and verbal memory recalling tasks more generally. On the other hand, the analyses of dimensionality and the larger measurement uncertainties in the CSEs for the backward sequences suggest that caution is needed when attempting to unify a single unidimensional construct based on forward and backward sequences with visuo-spatial and verbal memory tasks.

Why?

Society's need for knowledge about experiences, feelings, behaviours and abilities is increasing. It is important to know how people and society feel or how a product or service is perceived, and to be able to compare how these change over time and between different areas, for example when making decisions about priorities, efforts and effects. In order for measurements of experiences, feelings, behaviours and abilities to be useful and provide reliable data, quality-assured measurement is required for socalled category based measurements1. It is therefore necessary that basic measurement principles are applied, which is often not the case today in this field. For the physical quantities (length, mass, time, etc.) there has long been an internationally established measurement quality infrastructure. In Sweden, it is mainly RISE as the National Metrological Institute which, through its national measurement sites, is responsible for ensuring access to quality-assured and traceable measurements for society. However, the corresponding measurement quality infrastructure is so far missing for category based measurements.

What?

RISE has been working for several years to develop methodology and working methods for measurement quality assurance of experiences, feelings, behaviours and abilities. Through dialogue over several years with actors at various levels, including in health care and academia, it has emerged that there is a great need for support for this development. RISE has therefore produced a first draft of a possible sustainable organization for measurement quality assurance of category based measurements. A national centre for quality assurance of category based measurements would be tasked with coordinating and ensuring reliable and comparable measurements of experiences, feelings, behaviours and abilities. Such infrastructural support must make methodologies available to enable quality assurance for category based measurements. The organization must meet society's need for support by offering services based on internationally accepted metrological principles and scientific methods, as well as adopting a neutral and independent role.

How?

We have humility about the fact that it is a long process to establish an organization for category based measurements and that it needs to happen through a dynamic and iterative development in co-creation with the actors involved. We look forward to continuing to develop ideas and revise the proposal in dialogue in the coming years. It is also important to start a dialogue together with relevant actors about how the implementation of the organization can take place in the future.

Varför?

Samhällets behov av kunskap om upplevelser, känslor, beteenden och förmågor ökar. Det är viktigt att veta hur personer och samhället mår eller hur en produkt eller tjänst upplevs samt att kunna jämföra hur detta förändras över tid och mellan olika områden, för att exempelvis fatta beslut om prioriteringar, insatser och effekter. För att mätningar av upplevelser, känslor, beteenden och förmågor ska vara användbara och ge tillförlitliga underlag krävs kvalitetssäkrad mätteknik för s.k. kategoribaserade mätningar. Det är alltså nödvändigt att grundläggande mättekniska principer tillämpas, vilket ofta inte är fallet i dag inom detta område. För de fysikaliska storheterna (längd, massa, tid etc.) finns sedan länge en internationellt etablerad mätkvalitetsinfrastruktur. I Sverige är det huvudsakligen RISE som Nationellt Metrologiskt Institut som genom sina riksmätplatser ansvarar för att säkerställa tillgång till kvalitetssäkrade och spårbara mätningar för samhället. Motsvarande mätkvalitetsinfrastruktur saknas dock för kategoribaserade mätningar.

Vad?

RISE arbetar sedan flera år för att utveckla metoder och arbetssätt för mätkvalitetssäkring av upplevelser, känslor, beteenden och förmågor. Genom dialoger med aktörer på olika nivåer, bland annat inom hälso- och sjukvården och akademin, som pågått under flera års tid har det framkommit att det finns ett stort behov av stöd för denna utveckling. RISE har därför tagit fram ett första utkast för en möjlig hållbar organisering för mätkvalitetssäkring av kategoribaserade mätningar. Ett nationellt centrum för mätkvalitetssäkring av kategoribaserade mätningar skulle ha i uppdrag att samordna och säkerställa tillförlitliga och jämförbara mätningar av upplevelser, känslor, beteenden och förmågor. Ett sådant infrastrukturellt stöd ska tillgängliggöra metodiker för att möjliggöra mätkvalitetssäkring för kategoribaserade mätningar. Organiseringen ska möta samhällets behov av stöd genom att erbjuda tjänster baserade på internationellt vedertagna mättekniska principer och vetenskapliga metoder samt ha en neutral och oberoende roll.

Hur?

Det finns en stor ödmjukhet kring att det är en lång process att etablera en organisering för kategoribaserade mätningar och att det behöver ske genom en dynamisk och iterativ utveckling i samskapande med berörda aktörer. Vi ser fram emot att fortsätta utveckla tankar och revidera förslaget i dialog under kommande år. Det är också viktigt att påbörja en dialog tillsammans med relevanta aktörer om hur implementeringen av organiseringen kan ske i framtiden.

New candidate diagnostics for cognitive decline and dementia have recently been proposed based on effects such as primacy and recency in word learning memory list tests. The diagnostic value is, however, currently limited by the multiple ways in which raw scores, and in particular these serial position effects (SPE), have been defined and analyzed to date. In this work, we build on previous analyses taking a metrological approach to the 10-item word learning list. We show i) how the variation in task difficulty reduces successively for trials 2 and 3, ii) how SPE change with repeated trials as predicted with our entropy-based theory, and iii) how possibilities to separate cohort members according to cognitive health status are limited. These findings mainly depend on the test design itself: A test with only 10 words, where SPE do not dominate over trials, requires more challenging words to increase the variation in task difficulty, and in turn to challenge the test persons. The work is novel and also contributes to the endeavour to develop for more consistent ways of defining and analyzing memory task difficulty, and in turn opens up for more practical and accurate measurement in clinical practice, research and trials.

Development of novel therapies for Alzheimer’s Disease (AD) is constrained by the lack of available methods for preclinical diagnosis, despite extensive research on biomarker identification. The EMPIR NeuroMET project unites National Measurement Laboratories, clinicians and academics, to overcome limitations in measurement methods and provide a better understanding of how to improve, combine and analyse measurements in AD diagnosis and treatment. Comparability through SI (System of International Units) traceability and uncertainty analysis is an, as yet, unmet requirement for regulatory approval of biomarkers, patient centred outcome measures, clinical thresholds and new therapeutic drugs. We will report on:

• Multimodal statistical analysis on blood, CSF and saliva biomarkers data from the NeuroMET cohort generated by using mass spectroscopy and immunoassay platforms, including a novel immunoassay approach to overcome matrix effects when relative quantification is not sensitive enough. A new digital PCR approach was developed to assess microRNAs quantities in blood to compare with established biomarkers.
• Progress towards the development of mass spectrometry reference measurement procedures traceable to the SI for t-tau and α-synuclein in cerebrospinal fluids.
• Development of ultrahigh field Magnetic Resonance Imaging and Spectroscopy protocols for increased spatial and spectral resolution and decreased uncertainty, and their application to the NeuroMET cohort.
• Improved cognitive assessment protocols, with improved metrological evaluation of cognitive performance scores and the development of construct specification equations for various cognitive protocols and biomarkers.
• Potential relationships between volumes of AD-related brain structures and neurometabolite concentrations with measured cognitive function.

Improved reference methods to underpin the production of calibrators and improve measurement comparability of established biomarkers has the potential to further the understanding of AD and boost research for disease modifying therapies.

Did you ever wonder how to account for biases such as ceiling eects in your (cognitive) data?

Metrological quality assurance of human-based responses is in its infancy and analyzing categorial data and other human responses is challenging. However, there is a need to tackle those challenges to ensure that decisions about health care are made correctly. Quality assured comparability, interoperability and decision-making can successfully be done by applying sound metrological approaches to enable traceability as well as stressing declaration of measurement uncertainties. In the seminar, we present metrological approaches to ensure quality assurance of categorical data,such as cognitive assessments and other human-reported responses. This is followed by a hands-onworkshop where you are welcome to bring your own or freely available data for analyses.

Alongside a lack clinically validated, minimally invasive diagnostic tools for early diagnosis and/or monitoring of disease progression in Alzheimer’s Disease (AD), there are no sound metrological assessment protocols and measurements for cognition, nor measurement comparability through SI (System of International Units), traceability and uncertainty for regulatory approval of biomarkers. As part of the on-going EMPIR HLT04 NeuroMET project in which several national metrology institutes work together with clinicians and academics to overcome specific measurement issues to improve diagnosis and disease progression, we describe here the justification for and development of the ‘NeuroMET Memory Metric’ (version 0.1).

Re-examination of traditional widely used ‘legacy’ cognitive assessment protocols using invariant measurement theory aims at more accurately capturing the patient’s cognitive ability and improving the analysis of correlations with various AD biomarkers. Two principal elements provide sound metrological underpinnings: (i) a correct formulation of a measurement model; and (ii) proper handling of the ordinal cognitive data. In turn, this enables formulation of novel construct specification equations for patient cognitive ability as a function of diverse biomarkers (e.g., in plasma, CSF and saliva together with MRI/MRS data) as well as for cognitive task difficult as a function of test design.

To further improve the accuracy in patient’s cognitive ability work is now in progress to develop a NeuroMET Memory Metric based on legacy cognitive assessments (e.g., MMSE, Corsi Block Test, Digital Span Test). This work can be ascribed a level-5 construct theory. This means the realization of more fit-for-purpose, better targeted and better administered cognitive measurement systems. It will also enable traceable calibration of both additional cognitive tasks as well as the effects of intervention (or disease progression) on the cognitive ability of each individual patient.

Prof. Leslie Pendrill has been the Head of Research of the Measurement Division at the SP Technical Research Institute of Sweden since 1985. His research work is concerned with fundamental metrology, in particular optoelectronic, laser, length, and mass measurements, while his applied metrology activities include optimized measurement uncertainty studies and the measurement of perception. He is actively involved in several internationalmetrology activities, holding leading roles such as currently the 2009–2012 Chair of the European Association of NationalMetrology Institutes (EURAMET) and earlier as Chair (2006–2008) of the International Union of Pure and Applied Physics (IUPAP) Commission on Symbols, Units, Nomenclature, Atomic Masses and Fundamental Constants (SUNAMCO). He has just become a member of the NCSLI Board as EURAMET Representative.

Is it realistic to aspire to the same kind of quality-assurance of measurement in person-centred care, currently being implemented in healthcare globally, as is established in the physical sciences and engineering? Ensuring metrological comparability (‘traceability’) and reliably declaring measurement uncertainty when assessing patient ability or increased social capital are however challenging for subjective measurements often characterised by large dispersion. Drawing simple analogies between ‘instruments’ in the social sciences – questionnaires, ability tests, etc.–  and  engineering instruments such as thermometers does not go far enough. A possible way forward apparently equally applicable to both physical and social measurement, seems to be to model inferences in terms performance metrics of a measurement system. Person-centred care needs person-centred measurement and a full picture of the measurement process when Man acts as a measurement instrument is given in the present paper. This complements previous work by presenting the process, step by step, from the observed indication (e.g. probability of success, P_success, of achieving atask), through restitution with Rasch Measurement Theory, to the measurand (e.g. task difficulty). Rasch invariant measure theory can yield quantities –‘latent’ (or ‘explanatory’) variables such as task challenge or person ability – with characteristics akin to those of physical quantities. Metrological references for comparability via traceability and reliable estimates ofuncertainty and decision risks are then in reach even for perceptive measurements (and other qualitative properties). As a case study, the person-centred measurement of cognitive ability is examined, as part of the EUproject EMPIR 15HLT04 NeuroMet, for Alzheimer’s, where better analysis of correlations with brain atrophy is enabled thanks to the Rasch metrological approach.

Demands for quality assured measurement are increasing, not only from sectors such as health care, services and safety, where the human factor is obvious, but also from manufacturers of traditional technical products of all kinds who realize the need to assure the quality of their products as perceived by the customer. The metrology of human-based observations is however in its infancy. This article reviews how this can be tackled with a measurement system analysis approach, particularly where Man acts as a measurement instrument. Connecting decision risks when handling qualitative observations with information theory, perceptive choice and generalized linear modelling – through the Rasch invariant measure approach – enables a proper treatment of ordinal data and a clear separation of person and item attribute estimates. This leads in turn to opportunities of establishing measurement references, and the metrological quality assurance that is urgently needed in many contemporary applications.

Intensified cooperation amongst the national metrology institutes of Europe in all their fields of activity, from metrological research to calibration services, is a response to increased needs of society for traceable measurement, not only in the traditional areas (trade, manufacturing) but also in meeting the ‘Grand Challenges’ of modern society, such as Energy & the Environment; Health and Security, often in combination with the enabling technologies. European metrology had been coordinated successfully since 1987 by the European Association of National Metrology Institutes (EUROMET) but with increased integration of national programmes, a change of organisational form became necessary and since 2007 EURAMET e.V. is its successor as the Regional Metrology Organisation (RMO) of Europe.