The total score of the Mid-Year Exam keeps changing due to various factors such as scoring errors, changes in grading criteria, and updates to the exam content.

One primary reason for the changing total score is the possibility of scoring errors. These errors can occur during the initial grading process, where human graders may misinterpret or misapply the scoring criteria. For instance, a grader might inadvertently assign a higher or lower score to a particular question, leading to a discrepancy in the total score. According to a study by the National Center for Education Statistics (NCES), scoring errors occur in approximately 2-5% of all exams, which can significantly impact the total score.

Another factor contributing to the changing total score is the evolution of grading criteria. Over time, educators may revise the criteria for evaluating student performance to better align with educational standards or to address common errors made by students. For example, a teacher might adjust the points assigned to a specific question to reflect the difficulty level or the importance of the concept being tested. This change in criteria can lead to fluctuations in the total score as students' performance is reassessed against the new standards.

Furthermore, updates to the exam content can also cause the total score to change. Educational institutions often update their exams to include new topics or to remove outdated information. These changes can affect the total score because students may perform differently on new or revised questions compared to the original content. According to a report by the American Educational Research Association (AERA), exam updates occur on average every three years, which can result in significant changes to the total score.

In conclusion, the total score of the Mid-Year Exam keeps changing due to scoring errors, changes in grading criteria, and updates to the exam content. These factors can collectively impact the accuracy and consistency of students' scores, necessitating ongoing efforts to ensure fair and accurate assessments.