Sequential decision bias - evidence from grading exams

Human perception is very comparative. A misperception of random sequential processes, however, can influence the outcome of important decisions in many areas of daily life, including the evaluation of exams in higher education. We investigate this effect by using an extensive dataset of more than 20,000 examination results that is analysed on whether a student's performance in an exam has an impact on the evaluation of the one following, e.g. whether a poor performance lets the following shine in a better light, resulting in a better-than-expected grade. We conclude that there is evidence for sequential decision biases that do not necessarily occur generally, but rather after streaks of extreme events. An even greater effect size is detected when limiting the sample to exams with a low variance in grades and to exams that were evaluated later in the exam correction sequence. Therefore, there is evidence that under certain conditions, past evaluations may impact on current evaluations of student performances. This study should raise awareness of biases in grading against the background of their importance in the assessment of students' educational performances, the admission to consecutive study programmes and as a key metric in the evaluation of job candidates.