Description
probability = wrongPenalty/(correctAward+wrongPenalty), the success probability giving zero expected score for an attempted binary correct/wrong outcome.
Scoring rules combine points, item weights, boundaries and policies for omission, extra credit or missing items. A computed mark is meaningful only under those explicit rules; applying a rule does not establish its fairness or official status.
probability = wrongPenalty/(correctAward+wrongPenalty), the success probability giving zero expected score for an attempted binary correct/wrong outcome.
When to use this tool
Use Negative Marking Neutral Guess Probability when checking one supplied scoring contribution or policy boundary.
How to use the tool and how it works
- Enter correctAward, wrongPenalty. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read probability. Use the output convention below.
Require nonnegative correctAward and wrongPenalty with positive sum. probability = wrongPenalty/(correctAward+wrongPenalty), the success probability giving zero expected score for an attempted binary correct/wrong outcome.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| correctAward | Correct Award | Required. Finite number; minimum 0. |
| wrongPenalty | Nonnegative magnitude deducted for a wrong answer. | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| probability | Dimensionless probability from zero to one under the stated model. | Required. Finite number. |
{
"input": {
"correctAward": 3,
"wrongPenalty": 1
},
"output": {
"probability": 0.25
}
}Limitations and assumptions
- Penalty is entered as a positive magnitude. Omission rewards, partial credit, risk preferences and actual test policy are omitted.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the complete approved rubric and score record for an official outcome, and examine measurement quality separately.
References
Similar or alternative tools
- Mastery Threshold Remaining Item Budget
Calculate the correct-item deficit and whether a supplied mastery-count target remains reachable.
- Rubric Interval Boundary Tie
Return band upper when score > threshold, or when score equals threshold and equalityToUpper is true; otherwise return lower.