Partial Scoring of Reordering Tasks : Maximal Relative Sequence by Excel

摘要

An Excel form was developed by the author for calculating partial scoring of item reordering questions. It is a transplant of the algorithm realised in an application also devised by the author for the same purpose of calculation. Whereas the computer application is quick and efficient, the internal mechanism is a blackbox to general users unless the coding is understood. The present tool shows explicitly how each step of calculation is combined to reach the final score, together with possible combinations of partially correct elements within a target sequence. Given a correct answer A-B-C-D-E, a test-taker answer C-D-A-B-E, for instance, will be evaluated for two partial sequences C-D-E or A-B-E. In these partial sequences (Maximal Relative Sequences), elements run in an ascending order while allowing gaps, and they are the longest possible sequences. The partial score is 2, counting the number of transitions of elements, out of the full score of 4. Any MRS is a result of dislocating elements from the correct answer, which is measurable by `Minimal Edit Distance' (MED). Unlike MED, MRS is locally calculable and therefore eligible for Excel transplantation. This paper explains how each step of forming an MRS is conducted. Despite limitations of memory, the present Excel form is a popular tool which helps users to understand the rationale behind MRS, and of more practical significance it is a convenient tool to get partial scores by simply copying and pasting test-taker answers.