# Question statistics Synap's Questions statistics page can be found on all exams, this page is designed to provide you with a deeper insight into the performance on individual questions within an exam. Learn how users are interacting with questions and make informed decisions about content adjustments, tagging and overall quality assurance. Head over to an exam with completed attempts and use the sub menu to navigate to 'Questions'.

From the question statistics page you can minimise the sub menu to make the most of the space on screen.

### Columns and data Use the Manage columns drop down to select which columns to have shown or hidden, different question types have different statistics and information available to view

The table below summarises the different columns and what they display. As a quick reminder on credits and points: * **Points** - Are what is awarded for a correct / partially correct response. If negative marking is being used then points are what are deducted for an incorrect answer * **Credits** - The maximum points up for grabs for answering a question correctly

| Column | Description | | ---------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Question stem | A preview of the question as it appeared in the exam (open the toggle to view) | | Average credits | The average number of credits achieved by users in this exam on this question | | Max credits | The maximum number of points that can be awarded for a correct answer | | Partial credits | The number of points awarded for a partially correct answer | | Negative scoring | The number of credits deducted for an incorrect response | | Average score | The average percentage score of the question in this exam | | EMQ | The EMQ group the question belonged to (if any) | | Section | The section ID the question belongs to (if any) | | Subject, Topic, Subtopic, Skill and Difficulty | The faceted tag/s set on the question (if any) | | Total | The total number times the question appeared in completed exam attempts | | Responses |

The number of times the question was answered correct, incorrect, partially correct, or skipped

| | Option breakdown | The number of times each answer option was selected for this question during this exam | | Statistics: Chance | The probability of guessing the correct answer, this is based on the number of possible answers with a single correct answer | | Statistics: P-Value | Item difficulty index ranges from 0 to 1, the higher the p-value the easier the question | | Statistics: Type | The discrimination type will either be the Pearson or Rpb (point biserial). Rpb is a special case of the Pearson's correlation used when the question only has two possible outcomes (correct or incorrect). Pearson will be displayed when there are 15+ responses, and candidates received correct, incorrect, or partial marks, Rpb will be displayed when there are 15+ responses, and candidates received only correct or incorrect marks. | | Statistics: Value | The discrimination index is a measure of the correlation between success in a particular question and success in the entire exam, and ranges from -1 to 1. The higher the value the better the question discrimination between high and low performing candidates. A negative value suggests low performing candidates are more likely to answer the question correctly than high performing candidates. These values will be displayed when there are 15++ responses. | ### Navigating the stats page Search by ID or External ID using the search bar and use the toggle to expand each question in more detail. Questions that require manual marking don't have an aggregated response to show.

{% hint style="info" %} Remember when creating exams, the questions are cloned from the source quiz or quizzes at the time of creation, so any edits you make to questions after the exam has been created won't be pulled through. This means your question stats page could look different to your actual questions if they have been updated. {% endhint %} ### Understanding Questions Statistics Synap provides two key psychometric measures to help evaluate question quality: 1.**Item Difficulty Index** (P-Value) & 2.**Item Discrimination** (Rpb or Pearson Correlation) #### 1.Item Difficulty Index (P-Value) **Formula:** ``` P = Number of Correct Responses ÷ Total Number of Responses ``` **Range:** * `0.00` = No candidates answered correctly (very difficult) * `1.00` = All candidates answered correctly (very easy) **Important Notes:** * P-values are **calculated from actual response data**, not from question settings. * If a P-value is unexpectedly `0.00` or `1.00`, check: * That the correct answer is set in the question editor * That the question has been attempted and marked correctly * Partial credit **does not affect** the P-value — a candidate must receive **full marks** to count as a correct response. #### **2.Item Discrimination (Rpb or Pearson Correlation)** **Definition:**\ Item discrimination measures how well a question **differentiates between high- and low-performing candidates**. In other words: do stronger candidates tend to get this question right? **How it's Calculated in Synap:** * **Point Biserial (Rpb):** Used when a question has only **correct or incorrect outcomes** (i.e. full marks or no marks). * **Pearson Correlation:** Used when a question allows for **partial marks** (e.g. multi-mark, multi-step). **Requirements:** * Discrimination values are only shown when a question has received at least **15 valid responses** to ensure statistical reliability. **Interpretation Guide:** | Discrimination Value | Interpretation | | -------------------- | ------------------------------------------ | | **≥ 0.40** | Very good discrimination | | **0.30 – 0.39** | Good | | **0.20 – 0.29** | Fair | | **< 0.20** | Low — may need review | | **< 0.00** | Negative — likely an issue (e.g. miskeyed) | **Why 15+ Responses?**\ Correlation-based stats (Rpb or Pearson) can be **unstable with small sample sizes**. Fewer than 15 responses can result in misleading values — for example, a single outlier could skew the correlation significantly. > Synap uses a 15-response threshold to ensure that item discrimination values are **statistically meaningful and actionable**.