Three Scoring Rules, Three Different Bets
A stepped plot of points earned against selections made for one modeled item with four correct options among eight: the zero-one line rises and then runs flat, the plus-minus line rises then steps down on each wrong click and flattens on a dashed floor labeled FLOOR = 0, and rationale scoring appears as four paired blocks, two filled and two hollow.
| PLUS-MINUS | ZERO-ONE | RATIONALE | |
|---|---|---|---|
| How credit accrues | Credit for each correct selection, a deduction for each incorrect one, and the item score cannot fall below zero. | A point for each correct response, with no deduction for a wrong one. | Credit depends on the linkage between two or three blanks, scored as a dyad or a triad. |
| What a wrong click costs | A point you had already earned, taken back. | Nothing beyond the point you did not get. | The whole pair. A correct condition attached to the wrong supporting evidence earns nothing. |
| What a blank costs | Only the credit it would have earned. Blanks are not punished. | A guaranteed zero on that cell. | The pair, because an incomplete link cannot be scored. |
| Which items use it | Extended multiple response, matrix multiple response, highlight in text. | Matrix multiple choice, drag-and-drop, drop-down scored per blank, bowtie, where five placements are worth five points. | Drop-down cloze items that pair a condition with the evidence for it. |
| The bet you should make | Select only what you can defend, because volume is taxed. | Never leave a cell empty; an unanswered cell is a donated point. | Choose the condition your evidence actually supports, not the condition you like best. |
Partial credit in one line
Case set items are scored polytomously, so a partly right answer is worth something real. A stand-alone traditional multiple-choice item is all or nothing, and no amount of good reasoning rescues a wrong click.
Working the difference
Take one uncertain option and run it through all three rules. Under zero-one you click it, because the worst case is the zero you already had. Under plus-minus you leave it, because a wrong click removes a point you earned somewhere else on the same item. Under rationale scoring the question is not whether the option is true; it is whether it is the evidence for the condition sitting in the other blank. The same uncertainty, three different clicks. That reflex is the whole point of this page.
Watch outOver-selecting on a highlight item is the fastest way to score zero on a question you mostly understood. Confidence and coverage are not the same thing, and only one of them is scored.
Margin noteguessing is free in one column only.
Item mechanics, type by type → BOOK 02 · P7. Test length and the pass rule → BOOK 01 · P6.
TakeawayUnder zero-one fill everything, under plus-minus select only what you can defend, and under rationale scoring the pairing is the answer.