The overall aim of this thesis is to demonstrate the usefulness and the efficacy of the Rasch model to provide solutions to a variety of measurement problems in the specific context of pain assessment. As Rasch models rest on the requirement of unidimensionality and as verbal self-report has been described as the most valid measure of the experience of pain (Melzack and Katz, 2006), all chapters of the present work focus on the measurement of a single dimension of the pain experience, its intensity and on self-reported rating scales assessing this dimension. Chapter 1 presents the basics of the Rasch methodology and describes how one model of the Rasch family of models, the many-facet model, can be applied to the analysis of pain intensity responses following CO2 laser heat stimulation. Several intensities of stimulation were delivered on the hand of one hundred subjects who had to rate their pain perception on a three-level verbal rating scale. This methodological chapter stressed the ability of the Rasch models to transform the original ordinal scores into linear measures on an interval scale. Advantages and disadvantages of the Rasch methodology are discussed. Chapter 2 presents a second application of the Rasch methodology: the development and validation of a new measurement tool. In that chapter, an item questionnaire, the Situational Pain Scale (SPS), measuring the mental representation of pain in imaginary painful situations was developed and validated with healthy and chronic pain adults. Chronic pain patients also completed questionnaires assessing clinical and emotional attributes. Responses to the SPS were analyzed according to the rating scale Rasch model to select unidimensional and unbiased items. The final SPS consisted of 18 items with a widespread measurement range, a distribution well-targeted for the sample of healthy subjects and chronic pain patients and a high index of measurement precision. The measure of pain representation was significantly related to present pain intensity and anxiety about pain. Fibromyalgia patients showed significantly higher pain representation measures than all other groups. The psychometric properties of the SPS allows to further test its value to predict behaviors such as chronification of an acute pain condition or coping strategies developed by the chronic pain patient Chapter 3 detailed a third application of the Rasch models: the investigation and optimization of rating scale functioning. It more specifically examines the question of the optimal number of response levels required to assess the intensity of pain. A first section details the problematic, reviews studies previously conducted and presents the statistical indexes provided by the Rasch methodology for investigating the functioning of rating scales. Two empirical studies follow. They investigate the optimal number of response levels required to assess the intensity of pain by means of the Rasch analysis. The first study is devoted to the examination of three verbal rating scales (four, five and ten response categories) in healthy adults rating the 18 items of the SPS (developed in chapter 2). Results showed that the 10- and the 5-level verbal rating scales (VRSs) were not effective to assess pain intensity but that the 4-level one was. Recategorization procedures applied on the 10- and the 5-level VRSs revealed that the optimal number of response levels was also around four. In conclusion, this study shows that the human being can only distinguish four response levels when assessing the pain intensity of hypothetical events on a VRS. The second empirical study is devoted to the examination of faces scales (FSs) in healthy children aged from four to seven years. Results of this second study showed an improvement in the ability to distinguish the response categories with age. The 4-5 year-old children could only distinguish two response categories and the 6-7 year-old children were able to discern the three levels of a three-level faces scale. In conclusion, young children do not distinguish as many faces as proposed by the majority of available faces scales. / L'objectif de cette thèse est de montrer l'utilité et l'efficacité du modèle de Rasch dans l'apport de solutions à divers problèmes rencontrés lors de la mesure de la douleur. Etant donné que le modèle de Rasch repose sur l'exigence d'unidimensionnalité et que l'auto-évaluation par le sujet a été décrite comme étant la mesure la plus valide de l'expérience de la douleur (Melzack and Katz, 2006), tous les chapitres de la thèse se sont focalisés sur la mesure d'une seule dimension de la douleur, son intensité, et sur les échelles d'auto-évaluation mesurant cette dimension. Le chapitre 1 présente les fondements de la méthodologie Rasch et décrit comment un des modèles de Rasch, le modèle multi-facettes, peut être appliqué à l'analyse de scores d'intensité de douleur fournis en réponse à des stimulations de chaleur délivrées à l'aide d'un laser CO2. Plusieurs intensités de stimulation ont été délivrées sur la main de cent sujets sains qui devaient évaluer leur perception de douleur sur une échelle verbale simple à trois niveaux de réponse. Ce chapitre méthodologique met l'accent sur la capacité du modèle de Rasch à transformer les scores originaux ordinaux en mesures linéaires sur une échelle d'intervalles. Les avantages et inconvénients de la méthodologie Rasch y sont discutés. Le chapitre 2 présente une seconde application de la méthodologie Rasch: le développement et la validation d'un nouvel instrument de mesure. Dans ce chapitre, un questionnaire, le Situational Pain Scale (SPS), mesurant la représentation mentale de la douleur lors de situations de douleur imaginaires est développé et validé dans une population d'adultes sains et de patients douloureux chroniques. Les patients douloureux chroniques ont également rempli une batterie de questionnaires évaluant diverses variables cliniques et émotionnelles. Les réponses au SPS ont été analysées à l'aide du modèle rating scale afin de sélectionner les items satisfaisant au critère d'unidimensionnalité et d'invariance de l'échelle. L'échelle finale comprend 18 items présentant une large étendue de mesure, une distribution bien ciblée par rapport à l'échantillon de sujets sains et de patients douloureux chroniques et une précision de mesure élevée. La mesure de la représentation de la douleur est significativement corrélée avec l'intensité de la douleur au moment de l'évaluation ainsi qu'avec l'anxiété spécifiquement liée à la douleur. Les patients fibromyalgiques ont une représentation de la douleur plus élevée que tous les autres groupes. Les qualités psychométriques de l'échelle permettent, dans le futur, de tester sa capacité à prédire certains comportements comme par exemple le risque de chronification d'un état de douleur aiguë ou encore les stratégies développées par le patient pour faire face à son état de douleur chronique. Le chapitre 3 détaille une troisième application des modèles de Rasch : l'investigation et l'optimisation du fonctionnement des échelles de réponse. Ce chapitre examine plus spécifiquement la question du nombre optimal de niveaux de réponse nécessaire pour évaluer l'intensité de la douleur. Une première section introduit la problématique, présente une revue de la littérature sur la question et détaille les indices statistiques fournis par la méthodologie Rasch pour étudier le fonctionnement des échelles de réponse. Deux études empiriques suivent. Elles étudient le nombre optimal de niveaux de réponse nécessaire pour l'évaluation de la douleur. La première étude est consacrée à l'investigation de trois échelles verbales simples (quatre, cinq et dix catégories de réponse) chez des adultes sains évaluant les 18 items du SPS dont le développement a été présenté au chapitre 2. Les résultats montrent que les échelles verbales simples (EVSs) à dix et cinq niveaux ne sont pas efficaces pour évaluer l'intensité de la douleur alors que l'échelle à quatre niveaux l'est. Les procédures de recatégorisation appliquées sur les EVSs à dix et cinq niveaux révèlent que le nombre optimal de niveaux de réponse est de quatre. En conclusion, cette étude montre que l'être humain ne peut distinguer que quatre niveaux de réponse lorsqu'il évalue des situations imaginaires sur une EVS. La seconde étude empirique est consacrée à l'investigation des échelles visages chez des enfants sains âgés de quatre à sept ans. Les résultats de cette seconde étude montrent une amélioration dans la capacité à distinguer les catégories de réponse avec l'âge. Les enfants de quatre et cinq ans ne peuvent distinguer que deux catégories de réponse alors que les enfants de six et sept ans peuvent distinguer les trois niveaux d'une échelle à trois visages. En conclusion, les jeunes enfants ne peuvent pas distinguer autant de visages que proposés par la majorité des échelles visages publiées.

Previous research into the accuracy of referrals for glaucoma has shown that a large number of referrals to the Hospital Eye Service are false positive. Research in areas of healthcare other than ophthalmology has shown that psychological distress can be caused by false positive referrals. The present study aimed to evaluate the quality of referrals to the HES for all ocular pathologies, and also to quantify the proportion of these referrals that were false positive. Any commonality between false positive referrals was investigated. The psychological effect of being referred to the HES was also evaluated using the Hospital Anxiety and Depression Scale (HADS) and State-Trait Anxiety Inventory (STAI). Both scales were validated in this population with Rasch analysis before use. A final aim was to develop an improvement to the present referral pathway in order to reduce numbers of false positive referrals. The accuracy of referrals to the HES appears to improve as clinicians become more experienced, and greater numbers of false positive referrals are generated by female clinicians. Optometrists refer patients with a wide range of ocular diseases and in most cases include both fundus observations and visual acuity measurements in their referrals. GPs mainly refer patients with anterior segment disorders, particularly lid lesions, based on direct observation and symptoms. Illegibility and missing clinical information reduce the quality of many optometric referrals. Patients referred to the HES experience raised levels of anxiety as measured by the STAI and raised levels of depression as measured by the HADS-Depression subscale. As a method of assessing psychological distress, the questionnaires HADS-T (all items), STAI-S (State subscale) and STAI-T (Trait subscale) show good discrimination between patients when administered to a population of new ophthalmic outpatients, despite all having a floor effect. Subsequently a referral refinement service was developed which reduced numbers of unnecessary referrals and reduced costs for the NHS.

<p>One of the key ideas in the research on mathematics education is that the mathematical knowledge that learners acquire is strongly tied to the particular situation in which it is learnt. This study investigated the contexts that learners in grades eight, nine and ten prefer to deal with in the learning of mathematics based on their personal, social, societal, cultural and contextual concerns or affinities. The study is situated in the large-scale project called the Relevance of School Mathematics Education II (ROSMEII), which is concerned with the application and the use of mathematical knowledge and processes in real life situations. It is based on a survey of learners from ten (10) secondary schools in the Oshana and Khomas regions of Namibia. The ten schools that were sampled represent the spectrum of schools in Namibia in both urban and semi-urban areas. The Rasch model of data analysis is employed to provide some insight into the contextual situations learners would like to deal with in their mathematical learning. The data obtained for this study was analysed using the WINSTEPS Version 3.65.0 suite of computer programs. The current study arises from a concern about the absence of the voices of learners in the contextual situations in mathematics selected by adults such as mathematics teachers, inspectorates and curriculum and materials developers. The assumption is that the inclusion of learners&rsquo / insights into mathematics curricular might enhance mathematical learning. The study reveals that school children have an intrinsic desire to learn about mathematical issues embedded in real-life contexts. Several items which Namibian learners have shown interest in are issues they experience in life out of school which are not directly dealt with in school, such as managing personal and financial affairs, health matters, technology, construction, engineering and government financial matters. However, learners indicated to have a low preference in contexts like lotteries and gambling, national and international politics, cultural products, all kinds of pop music and dancing. This thesis contends that the inclusion of contexts in the mathematics curriculum which are of interest to learners will go a long way in facilitating good performance of learners in mathematics.</p>

<p>One of the key ideas in the research on mathematics education is that the mathematical knowledge that learners acquire is strongly tied to the particular situation in which it is learnt. This study investigated the contexts that learners in grades eight, nine and ten prefer to deal with in the learning of mathematics based on their personal, social, societal, cultural and contextual concerns or affinities. The study is situated in the large-scale project called the Relevance of School Mathematics Education II (ROSMEII), which is concerned with the application and the use of mathematical knowledge and processes in real life situations. It is based on a survey of learners from ten (10) secondary schools in the Oshana and Khomas regions of Namibia. The ten schools that were sampled represent the spectrum of schools in Namibia in both urban and semi-urban areas. The Rasch model of data analysis is employed to provide some insight into the contextual situations learners would like to deal with in their mathematical learning. The data obtained for this study was analysed using the WINSTEPS Version 3.65.0 suite of computer programs. The current study arises from a concern about the absence of the voices of learners in the contextual situations in mathematics selected by adults such as mathematics teachers, inspectorates and curriculum and materials developers. The assumption is that the inclusion of learners&rsquo / insights into mathematics curricular might enhance mathematical learning. The study reveals that school children have an intrinsic desire to learn about mathematical issues embedded in real-life contexts. Several items which Namibian learners have shown interest in are issues they experience in life out of school which are not directly dealt with in school, such as managing personal and financial affairs, health matters, technology, construction, engineering and government financial matters. However, learners indicated to have a low preference in contexts like lotteries and gambling, national and international politics, cultural products, all kinds of pop music and dancing. This thesis contends that the inclusion of contexts in the mathematics curriculum which are of interest to learners will go a long way in facilitating good performance of learners in mathematics.</p>

Objectives: To explore the prevalence and structure of self-reported disability after mild traumatic brain injury and the impact of traumatic brain pathology on such outcome. Material and methods: In study 1-3, symptoms data were collected by use of Rivermead Post-concussion Symptoms Questionnaire (RPQ) and data on global function by use of Glasgow Outcome Scale Extended (GOSE) from 2602 patients at 3 months after MTBI. RPQ data were subject to factor and Rasch-analyses Head CT data from 1262 patients were used in a prediction analysis that also included age and gender. In study 4, MRI and symptoms data were collected at 2-3 days and at 3-7 months follow-up after MTBI in 19 patients. Global function was assessed at follow-up by use of the Rivermead Head Injury Follow-Up Questionnaire (RHIFUQ) and GOSE. Results: I. Most respondents reported no remaining symptoms but 24% reported ≥3 and 10% ≥7 remaining symptoms. The factor analysis demonstrated that all symptoms are correlated but also identified subgroups of symptoms. II. Rasch-analysis of RPQ showed disordered category function, local dependency of items, poor targeting of persons to items and indications of 3 or more dimensions. There was no differential item functioning. III. Head CT pathology with no need for acute intervention was observed in 52 patients (4%) but was not associated with either frequency of remaining symptoms or global outcome at 3 months post injury. Female gender and age over 30 years were associated with less favourable outcome with respect to symptoms and GOSE. IV. Post-acute MRI indicated trauma-related pathology in one patient and follow-up MRI indicated loss of brain volume in 4 patients. Conclusions: A substantial proportion of patients with MTBI report remaining problems at three months after MTBI. RPQ is useful but not optimal to assess symptoms outcome after MTBI and calculation of a total sum score is not recommended. Female gender and older age are negative prognostic factors while brain pathology according to CT has no effect on self-reported outcome. Loss of brain volume after MTBI according to MRI may be a sensitive marker of traumatic brain pathology and deserves further studies.

Magister Educationis - MEd / One of the key ideas in the research on mathematics education is that the mathematical knowledge that learners acquire is strongly tied to the particular situation in which it is learnt. This study investigated the contexts that learners in grades eight, nine and ten prefer to deal with in the learning of mathematics based on their personal, social, societal, cultural and contextual concerns or affinities. The study is situated in the large-scale project called the Relevance of School Mathematics Education II (ROSMEII), which is concerned with the application and the use of mathematical knowledge and processes in real life situations. It is based on a survey of learners from ten (10) secondary schools in the Oshana and Khomas regions of Namibia. The ten schools that were sampled represent the spectrum of schools in Namibia in both urban and semi-urban areas. The Rasch model of data analysis is employed to provide some insight into the contextual situations learners would like to deal with in their mathematical learning. The data obtained for this study was analysed using the WINSTEPS Version 3.65.0 suite of computer programs. The current study arises from a concern about the absence of the voices of learners in the contextual situations in mathematics selected by adults such as mathematics teachers, inspectorates and curriculum and materials developers. The assumption is that the inclusion of learners’ insights into mathematics curricular might enhance mathematical learning. The study reveals that school children have an intrinsic desire to learn about mathematical issues embedded in real-life contexts. Several items which Namibian learners have shown interest in are issues they experience in life out of school which are not directly dealt with in school, such as managing personal and financial affairs, health matters, technology, construction, engineering and government financial matters. However, learners indicated to have a low preference in contexts like lotteries and gambling, national and international politics, cultural products, all kinds of pop music and dancing. This thesis contends that the inclusion of contexts in the mathematics curriculum which are of interest to learners will go a long way in facilitating good performance of learners in mathematics. / South Africa

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No / Patient-reported outcome measurement has become accepted as an important component of comprehensive outcomes research. Researchers wishing to use a patient-reported measure must either develop their own questionnaire (called an instrument in the research literature) or choose from the myriad of instruments previously reported. This article summarizes how previously developed instruments are best assessed using a systematic process and we propose a system of quality assessment so that clinicians and researchers can determine whether there exists an appropriately developed and validated instrument that matches their particular needs. These quality assessment criteria may also be useful to guide new instrument development and refinement. We welcome debate over the appropriateness of these criteria as this will lead to the evolution of better quality assessment criteria and in turn better assessment of patient-reported outcomes.

Previous research into the accuracy of referrals for glaucoma has shown that a large number of referrals to the Hospital Eye Service are false positive. Research in areas of healthcare other than ophthalmology has shown that psychological distress can be caused by false positive referrals. The present study aimed to evaluate the quality of referrals to the HES for all ocular pathologies, and also to quantify the proportion of these referrals that were false positive. Any commonality between false positive referrals was investigated. The psychological effect of being referred to the HES was also evaluated using the Hospital Anxiety and Depression Scale (HADS) and State-Trait Anxiety Inventory (STAI). Both scales were validated in this population with Rasch analysis before use. A final aim was to develop an improvement to the present referral pathway in order to reduce numbers of false positive referrals. The accuracy of referrals to the HES appears to improve as clinicians become more experienced, and greater numbers of false positive referrals are generated by female clinicians. Optometrists refer patients with a wide range of ocular diseases and in most cases include both fundus observations and visual acuity measurements in their referrals. GPs mainly refer patients with anterior segment disorders, particularly lid lesions, based on direct observation and symptoms. Illegibility and missing clinical information reduce the quality of many optometric referrals. Patients referred to the HES experience raised levels of anxiety as measured by the STAI and raised levels of depression as measured by the HADS-Depression subscale. As a method of assessing psychological distress, the questionnaires HADS-T (all items), STAI-S (State subscale) and STAI-T (Trait subscale) show good discrimination between patients when administered to a population of new ophthalmic outpatients, despite all having a floor effect. Subsequently a referral refinement service was developed which reduced numbers of unnecessary referrals and reduced costs for the NHS.