Effect a negative score on the exam results: A case report

The main assumption in the exam scoring system consists of multiple choice questions is that the number of choice is limited, so if the student don’t knows the correct answer can guess it. The most common way to stop guessing, assigning a negative score. The aim of this study was to investigate the effect of negative score on the results of an exam. This article is descriptive study of student score and grades before and after applying a negative score, and then again after the changes done by the Department of Basic Sciences. Encompassing 58 scores entered in SPSS v19 and analyzed using paired t-test was performed. To clarify the relationship between students rank, the Spearman correlation test was used. The mean score before and after applying a negative score, and then again after the changes done by the Department are 11.59 ± SD 2.34, 10.90 ± SD 2.14 and 12.45 ± SD 2.19, respectively. T test results showed statistically significant differences between the mean scores of the three modes. (P value for all three <0.001) Spearman correlation coefficients between three models are the 0.94, 0.94 and 0.98 (P value for all three 0.001) Although the use of correction formulas has its fans, but the results of this study and the related literature indicates, using the correct formula for the prevention of guessing is not recommended to increase the credibility and differentiation and other methods may be used.