Thursday, November 18, 2010
All Most Unexpected Responses
Ministep prints out two identical Tables, 6.6 and 10.6, showing additional, less unexpected, responses to those in Table 6.5, persons, and Table 10.5, items. These less most unexpected wrong responses have been added in yellow to PUP Table 3 Student Counseling Mark Matrix with Scores and Item Difficulties.
Also four unexpected right answers are added in green. They raise the question, “How did these low scoring students manage to make right marks on these two difficult items?” Was it luck, guessing, copying or an accurate report of knowledge? This question cannot be answered with the combined evidence from Winsteps posted on PUP Table 3.
Student marks that fit the Rasch model the best reside along a line separating yellow and uncolored wrong marks. Red and green marks contribute the most to unfitness in the model. This makes good sense.
High scoring students are assumed to be careless in making wrong marks (red). Less able students are expected to be careless too (yellow). Low scoring students are suspect when making right marks on difficult questions (green). These are basic expectations of IRT.
PUP includes a guessing monitor (a quality score for judgment, only with Knowledge and Judgment ScoringTM) and a copy detector (Sheets 8 and 9).