Schriftliche Prüfungen: Vorteile von Multiple True-False Fragen gegenüber Typ-A Fragen

Fragestellung/Einleitung: Prüfungen sind essentieller Bestandteil in der ärztlichen Ausbildung. Sie liefern wertvolle Informationen über den Entwicklungsprozess der Studierenden und wirken lernbegleitend und lernmodulierend [1], [2]. Bei schriftlichen Prüfungen dominieren derzeit Multiple Choice Fragen, die in verschiedenen Typen verwendet werden. Zumeist werden Typ-A Fragen genutzt, bei denen genau eine Antwort richtig ist. Multiple True-False (MTF) Fragen hingegen lassen mehrere richtige Antworten zu: es muss für jede Antwortmöglichkeit entschieden werden, ob diese richtig oder falsch ist. Durch die Mehrfachantwort scheinen MTF Fragen bestimmte klinische Sachverhalte besser widerspiegeln zu können. Auch bezüglich Reliabilität und dem Informationsgewinn pro Testzeit scheinen MTF Fragen den Typ-A Fragen überlegen zu sein [3]. Dennoch werden MTF Fragen bislang selten genutzt und es gibt wenig Literatur zu diesem Fragenformat. In dieser Studie soll untersucht werden, inwiefern die Verwendung von MTF Fragen die Nutzbarkeit (Utility) nach van der Vleuten (Reliabilität, Validität, Kostenaufwand, Effekt auf den Lernprozess und Akzeptanz der Teilnehmer) [4] schriftlicher Prüfungen erhöhen kann. Um die Testreliabilität zu steigern, sowie den Kostenaufwand für Prüfungen zu senken, möchten wir das optimale Bewertungssystem (Scoring) für MTF Fragen ermitteln. Methoden: Wir analysieren die Daten summativer Prüfungen der Medizinischen Fakultät der Universität Bern. Unsere Daten beinhalten Prüfungen vom ersten bis zum sechsten Studienjahr, sowie eine Facharztprüfung. Alle Prüfungen umfassen sowohl MTF als auch Typ-A Fragen. Für diese Prüfungen vergleichen wir die Viertel-, Halb- und Ganzpunktbewertung für MTF Fragen. Bei der Viertelpunktbewertung bekommen Kandidaten für jede richtige Teilantwort ¼ Punkt. Bei der Halbpunktbewertung wird ½ Punkt vergeben, wenn mehr als die Hälfte der Antwortmöglichkeiten richtig ist, einen ganzen Punkt erhalten die Kandidaten wenn alle Antworten richtig beantwortet wurden. Bei der Ganzpunktbewertung erhalten Kandidaten lediglich einen Punkt wenn die komplette Frage richtig beantwortet wurde. Diese unterschiedlichen Bewertungsschemata werden hinsichtlich Fragencharakteristika wie Trennschärfe und Schwierigkeit sowie hinsichtlich Testcharakteristika wie der Reliabilität einander gegenübergestellt. Die Ergebnisse werden ausserdem mit denen für Typ A Fragen verglichen. Ergebnisse: Vorläufige Ergebnisse deuten darauf hin, dass eine Halbpunktbewertung optimal zu sein scheint. Eine Halbpunktbewertung führt zu mittleren Item-Schwierigkeiten und daraus resultierend zu hohen Trennschärfen. Dies trägt zu einer hohen Testreliabilität bei. Diskussion/Schlussfolgerung: MTF Fragen scheinen in Verbindung mit einem optimalen Bewertungssystem, zu höheren Testreliabilitäten im Vergleich zu Typ A Fragen zu führen. In Abhängigkeit des zu prüfenden Inhalts könnten MTF Fragen einen wertvolle Ergänzung zu Typ-A Fragen darstellen. Durch die geeignete Kombination von MTF und Typ A Fragen könnte die Nutzbarkeit (Utility) schriftlicher Prüfungen verbessert werden.

Do multiple true-false items beat the commonly used one-best-answers questions regarding to the Ottawa Criteria for Good Assessment? Results of a literature review

Background: Multiple True-False-Items (MTF-Items) might offer some advantages compared to one-best-answer-questions (TypeA) as they allow more than one correct answer and may better represent clinical decisions. However, in medical education assessment MTF-Items are seldom used. Summary of Work: With this literature review existing findings on MTF-items and on TypeA were compared along the Ottawa Criteria for Good Assessment, i.e. (1) reproducibility, (2) feasibility, (3) validity, (4) acceptance, (5) educational effect, (6) catalytic effects, and (7) equivalence. We conducted a literature research on ERIC and Google Scholar including papers from the years 1935 to 2014. We used the search terms “multiple true-false”, “true-false”, “true/false”, and “Kprim” combined with “exam”, “test”, and “assessment”. Summary of Results: We included 29 out of 33 studies. Four of them were carried out in the medical field Compared to TypeA, MTF-Items are associated with (1) higher reproducibility (2) lower feasibility (3) similar validity (4) higher acceptance (5) higher educational effect (6) no studies on catalytic effects or (7) equivalence. Discussion and Conclusions: While studies show overall good characteristics of MTF items according to the Ottawa criteria, this type of question seems to be rather seldom used. One reason might be the reported lower feasibility. Overall the literature base is still weak. Furthermore, only 14 % of literature is from the medical domain. Further studies to better understand the characteristics of MTF-Items in the medical domain are warranted. Take-home messages: Overall the literature base is weak and therefore further studies are needed. Existing studies show that: MTF-Items show higher reliability, acceptance and educational effect; MTF-Items are more difficult to produce

Search, Seizure and (False?) Arrest: An Analysis of Fourth Amendment Remedies when Police can Plant Evidence

The Fourth Amendment prohibits unreasonable searches and seizures in criminal investigations. The Supreme Court has interpreted this to require that police obtain a warrant prior to search and that illegally seized evidence be excluded from trial. A consensus has developed in the law and economics literature that tort liability for police officers is a superior means of deterring unreasonable searches. We argue that this conclusion depends on the assumption of truth-seeking police, and develop a game-theoretic model to compare the two remedies when some police officers (the bad type) are willing to plant evidence in order to obtain convictions, even though other police (the good type) are not (where this type is private information). We characterize the perfect Bayesian equilibria of the asymmetric-information game between the police and a court that seeks to minimize error costs in deciding whether to convict or acquit suspects. In this framework, we show that the exclusionary rule with a warrant requirement leads to superior outcomes (relative to tort liability) in terms of truth-finding function of courts, because the warrant requirement can reduce the scope for bad types of police to plant evidence

False -positives and false-negatives in tests for trend

False-positive and false-negative values were calculated for five different designs of the trend test and it was demonstrated that a design suggested by Portier and Hoel in 1984 for a different problem produced the lowest false-positive and false-negative rates when applied to historical spontaneous tumor rate data for Fischer Rats. ^

Levine Suzanne Jill. Manuel Puig and the Spider Woman. His Life and Fictions. New York, Farrar, Straus and Giroux, 449 págs

Fil: Amícola, José. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Levine Suzanne Jill. Manuel Puig and the Spider Woman. His Life and Fictions. New York, Farrar, Straus and Giroux, 449 págs

Fil: Amícola, José. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Levine Suzanne Jill. Manuel Puig and the Spider Woman. His Life and Fictions. New York, Farrar, Straus and Giroux, 449 págs

Fil: Amícola, José. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

Epigeal spider occurrence, abundance and diversity in moist acidic and dry heath tundra at Toolik Lake, Alaska

For the 2004-2006 growing seasons, we trapped a total of 6980 spiders (5066 adults, 1914 immatures) using pitfall traps at the Arctic Long Term Experimental Research (LTER) site in Toolik Lake, Alaska. We found 10 families and 51 putative species, with 45 completely identified, in two distinct habitats: Moist Acidic Tundra (MAT) and Dry Heath (DH) Tundra. We captured spiders belonging to the following families (number of species captured): Araneidae (1), Clubionidae (1), Dictynidae (1), Gnaphosidae (4), Linyphiidae (26), Lycosidae (11), Philodromidae (2), Salticidae (1), Theridiidae (1), and Thomisidae (3). Statistical comparisons of families captured at MAT and DH Tundra indicate that the habitats have significantly different spider communities (Chi Square Test: p < 0.0001, and Fisher's Exact Test: p = 0.0018). This finding is further supported by differences in similarity, diversity, evenness, and species richness between the two habitats. In this report, we present eight new state records and five extensions of previously described ranges for spider species. The following species are new state records for Alaska: Emblyna borealis (O.P.-Cambridge 1877), Horcotes strandi (Sytschevskaja 1935), Mecynargus monticola (Holm 1943), Mecynargus tungusicus (Eskov 1981), Metopobactrus prominulus (O.P. -Cambridge 1872), Poeciloneta theridiformis Emerton 1911, and Poeciloneta vakkhanka (Tanasevitch 1989). The following five species have been reported previously in Alaska, but not near Toolik Lake: Hypsosinga groenlandica Simon 1889, Gnaphosa borea Kulczyn'ski 1908, Gnaphosa microps Holm 1939, Haplodrassus hiemalis (Emerton 1909), and Islandiana cristata Eskov 1987. Pairwise similarity indices were calculated across 13 other arctic and subarctic spider communities and statistical tests show that all sites are dissimilar (p = 0.25). These results fit the general pattern of both the patchiness and habitat specificity of arctic spider fauna.

Temperature tolerance of different larval stages of the spider crab Hyas araneus exposed to elevated seawater PCO2

Exposure to elevated seawater PCO2 limits the thermal tolerance of crustaceans but the underlying mechanisms have not been comprehensively explored. Larval stages of crustaceans are even more sensitive to environmental hypercapnia and possess narrower thermal windows than adults. In a mechanistic approach, we analysed the impact of high seawater CO2 on parameters at different levels of biological organization, from the molecular to the whole animal level. At the whole animal level we measured oxygen consumption, heart rate and activity during acute warming in zoea and megalopa larvae of the spider crab Hyas araneus exposed to different levels of seawater PCO2. Furthermore, the expression of genes responsible for acid-base regulation and mitochondrial energy metabolism, and cellular responses to thermal stress (e.g. the heat shock response) was analysed before and after larvae were heat shocked byrapidly raising the seawater temperature from 10°C rearing temperature to 20°C. Zoea larvae showed a high heat tolerance, which decreased at elevated seawater PCO2, while the already low heat tolerance of megalopa larvae was not limited further by hypercapnic exposure. There was a combined effect of elevated seawater CO2 and heat shock in zoea larvae causing elevated transcript levels of heat shock proteins. In all three larval stages, hypercapnic exposure elicited an up-regulation of genes involved in oxidative phosphorylation, which was, however, not accompanied by increased energetic demands. The combined effect of seawater CO2 and heat shock on the gene expression of heat shock proteins reflects the downward shift in thermal limits seen on the whole animal level and indicates an associated capacity to elicit passive thermal tolerance. The up-regulation of genes involved in oxidative phosphorylation might compensate for enzyme activities being lowered through bicarbonate inhibition and maintain larval standard metabolic rates at high seawater CO2 levels. The present study underlines the necessity to align transcriptomic data with physiological responses when addressing mechanisms affected by an interaction of elevated seawater PCO2 and temperature extremes.

Gene expression profiling in gills of the great spider crab Hyas araneus in respond to ocean acidification and warming, supplementary data

Hypercapnia and elevated temperatures resulting from climate change may have adverse consequences for many marine organisms. While diverse physiological and ecological effects have been identified, changes in those molecular mechanisms, which shape the physiological phenotype of a species and limit its capacity to compensate, remain poorly understood. Here, we use global gene expression profiling through RNA-Sequencing to study the transcriptional responses to ocean acidification and warming in gills of the boreal spider crab Hyas araneus exposed medium-term (10 weeks) to intermediate (1,120 µatm) and high (1,960 µatm) PCO2 at different temperatures (5°C and 10°C). The analyses reveal shifts in steady state gene expression from control to intermediate and from intermediate to high CO2 exposures. At 5°C acid-base, energy metabolism and stress response related genes were upregulated at intermediate PCO2, whereas high PCO2 induced a relative reduction in expression to levels closer to controls. A similar pattern was found at elevated temperature (10°C). There was a strong coordination between acid-base, metabolic and stress-related processes. Hemolymph parameters at intermediate PCO2 indicate enhanced capacity in acid-base compensation potentially supported by upregulation of a V-ATPase. The likely enhanced energy demand might be met by the upregulation of the electron transport system (ETS), but may lead to increased oxidative stress reflected in upregulated antioxidant defense transcripts. These mechanisms were attenuated by high PCO2, possibly as a result of limited acid-base compensation and metabolic down-regulation. Our findings indicate a PCO2 dependent threshold beyond which compensation by acclimation fails progressively. They also indicate a limited ability of this stenoecious crustacean to compensate for the effects of ocean acidification with and without concomitant warming.

Seawater carbonate chemistry and biological processes during experiments with spider crab Hyas araneus, 2011

The combined effects of ocean warming and acidification were compared in larvae from two populations of the cold-eurythermal spider crab Hyas araneus, from one of its southernmost populations (around Helgoland, southern North Sea, 54°N, habitat temperature 3-18°C; collection: January 2008, hatch: January-February 2008) and from one of its northernmost populations (Svalbard, North Atlantic, 79°N, habitat temperature 0-6°C; collection: July 2008, hatch: February-April 2009). Larvae were exposed to temperatures of 3, 9 and 15°C combined with present-day normocapnic (380 ppm CO2) and projected future CO2 concentrations (710 and 3,000 ppm CO2). Calcium content of whole larvae was measured in freshly hatched Zoea I and after 3, 7 and 14 days during the Megalopa stage. Significant differences between Helgoland and Svalbard Megalopae were observed at all investigated temperatures and CO2 conditions. Under 380 ppm CO2, the calcium content increased with rising temperature and age of the larvae. At 3 and 9°C, Helgoland Megalopae accumulated more calcium than Svalbard Megalopae. Elevated CO2 levels, especially 3,000 ppm, caused a reduction in larval calcium contents at 3 and 9°C in both populations. This effect set in early, at 710 ppm CO2 only in Svalbard Megalopae at 9°C. Furthermore, at 3 and 9°C Megalopae from Helgoland replenished their calcium content to normocapnic levels and more rapidly than Svalbard Megalopae. However, Svalbard Megalopae displayed higher calcium contents under 3,000 ppm CO2 at 15°C. The findings of a lower capacity for calcium incorporation in crab larvae living at the cold end of their distribution range suggests that they might be more sensitive to ocean acidification than those in temperate regions.