Item Difficulty Index  Is defined as the percentage or proportion of test takers who correctly answer the item.  For example, in a class of 30 stude
{"Image DocumentName": "Item Difficulty IndexIs defined as the percentage or proportion of test takers who correctly answer the item.", "Image ImageDescription": "For example, in a class of 30 students, if 20 students get the item correct and 10 are incorrect, the item difficulty index is 20/30 =0.67. Range from 0 to 1.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}