From 2009, CAT is conducted on multiple days and in multiple slots. So how candidates are ranked when they attempt different sets of questions at different points of time? This is a concern which many of must be you must be facing that how CAT exam is equated or normalized.
CAT Scoring system
A candidate will be awarded three marks for each correct answer and with every wrong answer, one mark will be deducted. However, there will be no penalty on unanswered questions.
Developing the CAT exam
Generally, a uniform difficulty level of the exam will be maintained throughout the days on which CAT will be conducted. The CAT exam is designed in such a manner (or difficulty) that no candidate would likely to answer 100 percent of the questions correctly or achieve the top theoretical score.
Equating the exam
IIMs mention that equating is a psychometric process to adjust differences in difficulty so that scores from different test forms are comparable on a common metric and therefore fair to candidates testing across multiple days. The equating process has designed with three phases: exam creation, post-equating, and scaling.
Each form contains a particular number of statistically-profiled questions selected from a large bank. These questions form an equating block which can be used as an anchor to re-scale candidates’ scores to the metric of the item bank. In the second phase, or in the post equating process, questions are analyzed and the difficulty level is put in a common metric. After the post equating process, the raw score is scaled to reduce confusion of candidates. Lastly, once scaled scores are established, the final step in the scoring process is to rank candidates in their performance. A percentile rank is the percentage of scores that fall below a given score. With the total scale scores arranged in rank order from the lowest to highest in 100 equally sized groups, a table with the total scale scores to percentile ranks will be created. This ranked list of candidates will allow for the identification of candidates from the highest performers at the very top of the list to the lower performers in the middle and low end of the scale.
Three-step scoring process which is an industry-standard and psychometrically-sound approach.
Step one: Raw scores are first calculated. These are derived by awarding three points for each correct answer and deducting one point for each incorrect answer. There is no penalty for omitted answers.
Step two: Raw scores are then adjusted for variances in difficulty levels across the different test forms through an equating process. Each form contains a pre-defined number of statistically-profiled questions selected from a large bank. Known as equating blocks, these have been designed to be equivalent based on their statistical properties, and allow us to measure how candidates taking different forms compare with each other when asked the same question. By looking at the performance of these equating blocks, we can adjust each candidate’s raw score and provide each of them with the score they would have earned had they taken the same form at the same time.
Step three: Equated scores are then placed on a common scale. Scaling creates a range of scores which can be used to create a percentile rank for the test as a whole and for each section.