Leniency and halo effects in marking undergraduate short research projects

BACKGROUND: Supervisors are often involved in the assessment of projects they have supervised themselves. Previous research suggests that detailed marking sheets may alleviate leniency and halo effects. We set out to determine if, despite using such a marking schedule, leniency and halo effects were evident in the supervisors' marking of undergraduate short research projects (special study modules (SSM)). METHODS: Review of grades awarded by supervisors, second markers and control markers to the written reports of 4(th )year medical students who had participated in an SSM during two full academic years (n = 399). Paired t-tests were used to compare mean marks, Pearson correlation to look at agreement between marks and multiple linear regression to test the prediction of one mark from several others adjusted for one another. RESULTS: There was a highly significant difference of approximately half a grade between supervisors and second markers with supervisors marking higher. (t = 3.12, p < 0.01, difference in grade score = 0.42, 95% CI for mean difference 0.18–0.80). There was a high correlation between the two marks awarded for performance of the project and the written report by the supervisor (r = 0.75), but a low-modest correlation between supervisor and second marker (r = 0.28). Linear regression analysis of the influence of the supervisors' mark for performance on their mark for the report gave a non-significant result. This suggests a leniency effect but no halo effect. CONCLUSIONS: This study shows that with the use of structured marking sheet for assessment of undergraduate medical students, supervisors marks are not associated with a halo effect, but leniency does occur. As supervisor assessment is becoming more common in both under graduate and postgraduate teaching new ways to improve objectivity in marking and to address the leniency of supervisors should be sought

Replication and Explorations of High-Order Epistasis Using a Large Advanced Intercross Line Pedigree

Dissection of the genetic architecture of complex traits persists as a major challenge in biology; despite considerable efforts, much remains unclear including the role and importance of genetic interactions. This study provides empirical evidence for a strong and persistent contribution of both second- and third-order epistatic interactions to long-term selection response for body weight in two divergently selected chicken lines. We earlier reported a network of interacting loci with large effects on body weight in an F2 intercross between these high– and low–body weight lines. Here, most pair-wise interactions in the network are replicated in an independent eight-generation advanced intercross line (AIL). The original report showed an important contribution of capacitating epistasis to growth, meaning that the genotype at a hub in the network releases the effects of one or several peripheral loci. After fine-mapping of the loci in the AIL, we show that these interactions were persistent over time. The replication of five of six originally reported epistatic loci, as well as the capacitating epistasis, provides strong empirical evidence that the originally observed epistasis is of biological importance and is a contributor in the genetic architecture of this population. The stability of genetic interaction mechanisms over time indicates a non-transient role of epistasis on phenotypic change. Third-order epistasis was for the first time examined in this study and was shown to make an important contribution to growth, which suggests that the genetic architecture of growth is more complex than can be explained by two-locus interactions only. Our results illustrate the importance of designing studies that facilitate exploration of epistasis in populations for obtaining a comprehensive understanding of the genetics underlying a complex trait

Effect of manipulation of primary tumour vascularity on metastasis in an adenocarcinoma model

One explanation for the clinical association between tumour vascularity and probability of metastasis is that increased primary tumour vascularity enhances haematogenous dissemination by offering greater opportunity for tumour cell invasion into the circulation (intravasation). We devised an experimental tumour metastasis model that allowed manipulation of primary tumour vascularity with differential exposure of the primary and metastatic tumour site to angiogenic agents. We used this model to assess the effects of local and systemic increases in the level of the angiogenic agent basic fibroblast growth factor on metastasis. BDIX rats with implanted hind limb K12/TR adenocarcinoma tumours received either intratumoural or systemic, basic fibroblast growth factor or saline infusion. Both intratumoural and systemic basic fibroblast growth factor infusion resulted in significant increases in tumour vascularity, blood flow and growth, but not lung metastasis, compared with saline-infused controls. Raised basic fibroblast growth factor levels and increase in primary tumour vascularity did not increase metastasis. The clinical association between tumour vascularity and metastasis is most likely to arise from a metastatic tumour genotype that links increased tumour vascularity with greater metastatic potential

Reduction of peritoneal carcinomatosis by intraperitoneal administration of phospholipids in rats

<p>Abstract</p> <p>Background</p> <p>Intraperitoneal tumor cell attachment after resection of gastrointestinal cancer may lead to a developing of peritoneal carcinosis. Intraabdominal application of phospholipids shows a significant decrease of adhesion formation even in case of rising tumor cell concentration.</p> <p>Methods</p> <p>In experiment A 2*10⁶colonic tumor cells (DHD/K12/Trb) were injected intraperitonely in female BD-IX-rats. A total of 30 rats were divided into three groups with treatments of phospholipids at 6% or 9% and the control group. In experiment B a total of 100 rats were divided into ten groups with treatments of phospholipids at 9% and the control group. A rising concentration of tumor cells (10,000, 50,000, 100,000, 250,000 and 500,000) were injected intraperitonely in female BD-IX-rats of the different groups. After 30 days, the extent of peritoneal carcinosis was determined by measuring the tumor volume, the area of attachment and the Peritoneal Cancer Index (PCI).</p> <p>Results</p> <p>In experiment A, we found a significant reduction (control group: tumor volume: 12.0 ± 4.9 ml; area of tumor adhesion: 2434.4 ± 766 mm²; PCI 28.5 ± 10.0) of peritoneal dissemination according to all evaluation methods after treatment with phospholipids 6% (tumor volume: 5.2 ± 2.2 ml; area of tumor adhesion: 1106.8 ± 689 mm²; PCI 19.0 ± 5.0) and phospholipids 9% (tumor volume: 4.0 ± 3.5 ml; area of tumor adhesion: 362.7 ± 339 mm²; PCI 13.8 ± 5.1). In experiment B we found a significant reduction of tumor volume in all different groups of rising tumor cell concentration compared to the control. As detected by the area of attachment we found a significant reduction in the subgroups 1*10⁴, 25*10⁴and 50*10⁴. The reduction in the other subgroups shows no significance. The PCI could be reduced significantly in all subgroups apart from 5*10⁴.</p> <p>Conclusion</p> <p>In this animal study intraperitoneal application of phospholipids resulted in reduction of the extent of peritoneal carcinomatosis after intraperitoneal administration of free tumor cells. This effect was exceptionally noticed when the amount of intraperitoneal tumor cells was limited. Consequently, intraperitoneal administration of phospholipids might be effective in reducing peritoneal carcinomatosis after surgery of gastrointestinal tumors in humans.</p

Residents Teaching Medical Students: How Do They Compare With Attending Educators?

PurposeEducating medical students is a core mission of academic radiology departments. In some programs, residents participate in student teaching. The aim of this study was to retrospectively compare medical student evaluations of radiology resident lectures with lecture evaluations of radiology faculty members.MethodsNumeric evaluations for lectures given by faculty members, fellows, and residents were collected over a 1-year period as part of routine course evaluations for a fourth-year medical student radiology elective. Faculty member, fellow, and resident lecture scores were compared, overall using analysis of variance and pairwise using Student's t test. A predefined low P-value threshold was used for the t tests to account for the multiple comparisons. To account for the inherent clustering of the data due to repeat lecturers, the data were reanalyzed on a "per lecturer" basis.ResultsThree hundred seven individual lecture scores were collected. There was no statistical difference between the lecture scores received by attending faculty members (mean, 9.10 on a scale of 10) and residents (mean, 8.99) (P = .08). Fellows, however, scored statistically significantly lower (mean, 8.45) than attending faculty members and residents (P &lt;.001 for both comparisons). The per lecturer analysis yielded similar results.ConclusionsLectures delivered by residents received similar evaluations as lectures delivered by faculty members. Given that teaching can be an educational experience for residents, involving radiology residents in medical student teaching may benefit students and residents alike