Rarely selected distractors in high stakes medical multiple-choice examinations and their recognition by item authors: A simulation and survey

Background Many medical exams use 5 options for multiple choice questions (MCQs), although the literature suggests that 3 options are optimal. Previous studies on this topic have often been based on non-medical examinations, so we sought to analyse rarely selected, 'non-functional' distractors (NF-D) in high stakes medical examinations, and their detection by item authors as well as psychometric changes resulting from a reduction in the number of options. Methods Based on Swiss Federal MCQ examinations from 2005-2007, the frequency of NF-D (selected by <1% or <5% of the candidates) was calculated. Distractors that were chosen the least or second least were identified and candidates who chose them were allocated to the remaining options using two extreme assumptions about their hypothetical behaviour: In case rarely selected distractors were eliminated, candidates could randomly choose another option - or purposively choose the correct answer, from which they had originally been distracted. In a second step, 37 experts were asked to mark the least plausible options. The consequences of a reduction from 4 to 3 or 2 distractors - based on item statistics or on the experts' ratings - with respect to difficulty, discrimination and reliability were modelled. Results About 70% of the 5-option-items had at least 1 NF-D selected by <1% of the candidates (97% for NF-Ds selected by <5%). Only a reduction to 2 distractors and assuming that candidates would switch to the correct answer in the absence of a 'non-functional' distractor led to relevant differences in reliability and difficulty (and to a lesser degree discrimination). The experts' ratings resulted in slightly greater changes compared to the statistical approach. Conclusions Based on item statistics and/or an expert panel's recommendation, the choice of a varying number of 3-4 (or partly 2) plausible distractors could be performed without marked deteriorations in psychometric characteristics.

Lifespan and disease predispositions in the Irish Wolfhound: a review

Several disease predispositions of Irish Wolfhounds are mentioned in the veterinary literature, but these lists vary greatly between different publications. This article reviews findings on lifespan as well as disease predispositions that have been reported in the literature. Hereditary mechanisms found so far are discussed, including their implications for breeding healthier dogs, the ethical necessity of which is stressed under the aspect of animal welfare. An open health registry, combined with the estimation of breeding values, seems to be the most promising approach. Furthermore, routine male castration is discouraged as being associated with an increased osteosarcoma risk. Mean lifespan estimates in Irish Wolfhounds vary between 4.95 and 8.75 years, but bias due to right censored data is common. The diseases reported to occur most frequently are dilated cardiomyopathy, osteogenic sarcoma, gastric dilation and volvulus and diseases of the osteochondrosis spectrum. Furthermore, intrahepatic portosystemic shunt plays an important role. Several other diseases have been reported in the literature, including rhinitis, epilepsy, progressive retinal atrophy, von Willebrand's Disease, and juvenile fibrocartilaginous embolism.