Mathematische Beweiskompetenzen Studierender diagnostizieren und fördern – eine Bestandsaufnahme

Mathematische Beweise bereiten vielen Studierenden große Schwierigkeiten. Bereits in den 70er Jahren wurden bei dieser Zielgruppe Untersuchungen durchgeführt und stehen auch aktuell wieder im Fokus vieler Studien (vgl. u. a. Schupp 1974, Platz et al. 2015). Auf bestehenden Erkenntnissen aufbauend wurden seit 2013 weitere Erhebungen mit Studierenden aus NRW durchgeführt. Die aktuellen Untersuchungen sind Bestandteile des Kooperationsprojektes eProof von Arbeitsgruppen der Universitäten Koblenz/ Landau und Münster (ausführliche Informationen zum Projekt: http://e-proof.weebly.com/). Die im Folgenden vorgestellten Ergebnisse folgen aus dem Teilprojekt BeSser „Beweiskompetenzen Studierender systematisch erweitern“, welches an der WWU Münster verortet ist. Ziel dieser Untersuchungen ist es, auf Basis der empirischen Befunde typische Fehler und Schwierigkeiten beim mathematischen Beweisen herauszustellen und daraus resultierende Konsequenzen zu erörtern

How do Non-Monetary Performance Incentives for Physicians Affect the Quality of Medical Care? – A Laboratory Experiment

In recent years, several countries have introduced non-monetary performance incentives for health care providers to improve the quality of medical care. Evidence on the effect of non-monetary feedback incentives, predominantly in the form of public quality reporting, on the quality of medical care is, however, ambiguous. This is often because empirical research to date has not succeeded in distinguishing between the effects of monetary and non-monetary incentives, which are usually implemented simultaneously. We use a controlled laboratory experiment to isolate the impact of nonmonetary performance incentives: subjects take on the role of physicians and make treatment decisions for patients, receiving feedback on the quality of their treatment. The subjects' decisions result in payments to real patients. By giving either private or public feedback we are able to disentangle the motivational effects of self-esteem and social reputation. Our results reveal that public feedback incentives have a significant and positive effect on the quality of care that is provided. Private feedback, on the other hand, has no impact on treatment quality. These results hold for medical students and for other students.In den vergangenen Jahren wurden in mehreren Ländern nicht-monetäre Leistungsanreize für Anbieter medizinischer Leistungen eingeführt, um die medizinische Versorgungsqualität zu verbessern. Die Wirkung nicht-monetärer Feedback-Anreize, vorwiegend in Form von öffentlichen Qualitätsberichten implementiert, ist jedoch nicht eindeutig belegt. Dies ist häufig darauf zurückzuführen, dass es in empirischen Studien bisher nicht gelang, die Effekte monetärer und nicht-monetärer Anreizen - in der Praxis meist gemeinsam implementiert - voneinander zu trennen. Wir führen ein kontrolliertes Laborexperiment durch, um den Einfluss von nicht-monetären Leitungsanreizen zu isolieren: Teilnehmer nehmen die Rolle eines Arztes ein und treffen Behandlungsentscheidungen für Patienten, wobei sie Feedback über die Qualität ihrer Behandlung erhalten. Die Entscheidungen der Teilnehmer führen zu Zahlungen an reale Patienten. Indem wir entweder privates oder öffentliches Feedback geben, können wir die Motivationseffekte von Selbstwertgefühl und sozialer Reputation voneinander trennen. Unsere Ergebnisse zeigen, dass öffentliche Feedback-Anreize einen signifikant positiven Effekt auf die bereitgestellte Behandlungsqualität haben. Privates Feedback hingegen hat keinen Einfluss auf die Behandlungsqualität. Diese Resultate gelten für Medizinstudenten sowie andere Studenten

Patient Preferences and Treatment Thresholds under Diagnostic Risk: An Economic Laboratory Experiment

We study risk-aversion and prudence in medical treatment decisions. In a laboratory experiment, we investigate the frequency and intensity of second- and third-order risk preferences, as well as the effect of the medical decision context. Risk preferences are assessed through treatment thresholds (the indifference point between not treating and treating). Under diagnostic risk, medical decision theory predicts lower treatment thresholds for risk-averse than for risk-neutral decision makers. Given a comorbidity risk in the sick state, prudent individuals have an even lower threshold. Our results demonstrate risk-averse and prudent behavior in medical decisions, which reduce the (average) treatment threshold by 41% relative to risk-neutrality (from 50.0% to 29.3%). Risk aversion accounts for 3/4 of this effect, prudence for 1/4. Medical decision framing does not affect risk aversion, but is associated with more and stronger prudent behavior. These findings can have consequences for diagnostic technologies and QALYs, and thus for clinical guidelines

How do Non-Monetary Performance Incentives for Physicians Affect the Quality of Medical Care? A Laboratory Experiment

In recent years, several countries have introduced non-monetary performance incentives for health care providers to improve the quality of medical care. Evidence on the effect of non-monetary feedback incentives, predominantly in the form of public quality reporting, on the quality of medical care is, however, ambiguous. This is often because empirical research to date has not succeeded in distinguishing between the effects of monetary and non-monetary incentives, which are usually implemented simultaneously. We use a controlled laboratory experiment to isolate the impact of non-monetary performance incentives: subjects take on the role of physicians and make treatment decisions for patients, receiving feedback on the quality of their treatment. The subjects decisions result in payments to real patients. By giving either private or public feedback we are able to disentangle the motivational effects of self-esteem and social reputation. Our results reveal that public feedback incentives have a significant and positive effect on the quality of care that is provided. Private feedback, on the other hand, has no impact on treatment quality. These results hold for medical students and for other students

Beweisen lernen durch lehren? - Chancen und Grenzen dieses Konzeptes

Die Unterrichtsmethode „Lernen durch Lehren” (LdL) beruht auf der Annahme, dass Schülerinnen und Schüler (SuS) und Studierende lernen, indem sie sich fachliche Inhalte gegenseitig vermitteln. Dieses Konzept soll auf das mathematische Beweisen innerhalb eines E-Proof-Systems übertragen werden. Es ergibt sich folgende wissenschaftliche Fragestellung: Führt die Einnahme der Lehrendenrolle zu einem besseren Verständnis von Beweiskonzepten und der Fähigkeit, logische Schritte strukturiert(er) aufzubauen und zu begründen

Impact of spot reduction on the effectiveness of rescanning in pencil beam scanned proton therapy for mobile tumours.

Objective. In pencil beam scanning proton therapy, individually calculated and positioned proton pencil beams, also referred to as 'spots', are used to achieve a highly conformal dose distributions to the target. Recent work has shown that this number of spots can be substantially reduced, resulting in shorter delivery times without compromising dosimetric plan quality. However, the sensitivity of spot-reduced plans to tumour motion is unclear. Although previous work has shown that spot-reduced plans are slightly more sensitive to small positioning inaccuracies of the individual pencil beams, the resulting shorter delivery times may allow for more rescanning. The aim of this study was to assess the impact of tumour motion and the effectiveness of 3D volumetric rescanning for spot-reduced treatment plans.Approach.Three liver and two lung cancer patients with non-negligible motion amplitudes were analysed. Conventional and probabilistic internal target volume definitions were used for planning considering single or multiple breathing cycles respectively. For each patient, one clinical and two spot-reduced treatment plans were created using identical field geometries. 4D dynamic dose calculations were then performed and resulting target coverage (V95%), dose homogeneity (D5%-D95%) and hot spots (D2%) evaluated for 1-25 rescans.Main results. Over all patients investigated, spot reduction reduced the number of spots by 91% in comparison to the clinical plan, reducing field delivery times by approximately 50%. This reduction, together with the substantially increased dose per spot resulting from the spot reduction process, allowed for more rescans in the same amount of time as for clinical plans and typically improved dosimetric parameters, in some cases to values better than the reference static (3D calculated) plans. However, spot-reduced plans had an increased possibility of interference with the breathing cycle, especially for simulations of perfectly repeatable breathing.Significance.For the patients analysed in this study, spot-reduced plans were found to be a valuable option to increase the efficiency of 3D volumetric rescanning for motion mitigation, if attention is paid to possible interference patterns

Inter-fractional Respiratory Motion Modelling from Abdominal Ultrasound: A Feasibility Study

Motion management strategies are crucial for radiotherapy of mobile tumours in order to ensure proper target coverage, save organs at risk and prevent interplay effects. We present a feasibility study for an inter-fractional, patient-specific motion model targeted at active beam scanning proton therapy. The model is designed to predict dense lung motion information from 2D abdominal ultrasound images. In a pretreatment phase, simultaneous ultrasound and magnetic resonance imaging are used to build a regression model. During dose delivery, abdominal ultrasound imaging serves as a surrogate for lung motion prediction. We investigated the performance of the motion model on five volunteer datasets. In two cases, the ultrasound probe was replaced after the volunteer has stood up between two imaging sessions. The overall mean prediction error is 2.9 mm and 3.4 mm after repositioning and therefore within a clinically acceptable range. These results suggest that the ultrasound-based regression model is a promising approach for inter-fractional motion management in radiotherapy