Comparative assessment of multiple choice questions versus short essay questions in pharmacology examinations.

This retrospective study compared the performance of medical students in multiple choice questions (MCQs) and short essay questions (SEQs). During the 3 year analysis, 533 students had an average score of 51.34% (SD 9.9) in the SEQ and 64.71%(SD 9.9)in the MCQs. Regression analysis showed a significant correlation(r=0.64, P<0.01) between MCQs and SEQs. When student performance was grouped by final course grade, a statistically significant correlation between MCQs and SEQs scores existed only for the 405 students who received a passing grade (r=0.21, P<0.01). The MCQ and SEQ scores were not correlated for the 128 students who failed (r=0.11, P=0.08) or for 70 students who achieved distinctions (r=-0.27, P=0.13). MCQ scores were significantly higher (P<0.01) than SEQ for each of the groups when analyzed by the two-way ANOVA test. The result of this study suggests that for most students, the strong correlation between MCQ and SEQ indicates that student performance was independent of testing format. For students at either end of the performance spectrum, the lack of correlation suggests that the performance in one of the testing format had a strong influence on the final course grade. In addition, those students who failed the course were likely to be weak in both testing modalities, whereas students in all grade groups were more likely to perform better in the MCQs than SEQs.

A 500 MHz proton NMR study of interaction of tripeptides Lys-Tyr-Lys and Lys-Phe-Lys with deoxydinucleotide d-CpG.

The binding of di- and tetranucleotides with tri- and tetrapeptides containing Tyr, Trp, Phe having lysine on both ends has been studied using a 500 MHz proton NMR. The results show that d-CpG exists as a right-handed B-DNA structure with both sugars in 01'-endo sugar conformation and glycosidic bond angle as in anti domain. On binding to tripeptide Lys-Tyr-Lys, the Tyr ring protons shift upfield by 0.015 ppm at 285 degrees K, while the conformation of d-CpG remains unchanged. Change in chemical shift of Tyr and nucleotide protons decreases with temperature. This upfield shift is attributed to stacking with bases/base-pairs. The presence of intermolecular NOE's also supports this. Results of binding of d-CpG to Lys-Phe-Lys are similar to those with Lys-Tyr-Lys except that the chemical shift changes occur to a lesser extent. On comparing the results obtained with three different peptides, it is found that interaction decreases in the order Trp > Tyr > Phe which is similar to that found by theoretical energy calculations (reported elsewhere) and fluorescence measurements. The results also exhibit a specificity in recognition of these amino acid residues by dinucleotides.