T/F: An item analysis can be performed before a test is administered. … What is calculated when you examine the proportion of test takers who get an item correct? **Difficulty index**. What is represented by the proportion of correct responses between the high and low groups?

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## How do you calculate item discrimination index?

The Discrimination Index (D) is computed from equal-sized high and low scoring groups on the test. **Subtract the number of successes by the low group on the item from the number of successes by the high group**, and divide this difference by the size of a group. The range of this index is +1 to -1.

## How do you calculate item analysis?

Determine the Discrimination Index by subtracting the number of students in the lower group who got the item correct from the number of students in the upper group who got the item correct. Then, **divide by the number of students in each group** (in this case, there are five in each group).

## What does a positive discrimination index indicate to test developers?

The difficulty index must also be negative. What does a positive discrimination index indicate to test developers? **a.** **More people in the high group got the item correct.**

## What is discrimination index of a test item?

Discrimination Index – The discrimination index is **a basic measure of the validity of an item**. It is a measure of an item’s ability to discriminate between those who scored high on the total test and those who scored low.

## What is the use of item analysis?

Item analysis is the **act of analyzing student responses to individual exam questions with the intention of evaluating exam quality**. It is an important tool to uphold test effectiveness and fairness.

## What is the objective of item analysis?

Item analyses are intended **to assess and improve the reliability of your tests**. If test reliability is low, test validity will necessarily also be low. This is the ultimate reason you do item analyses—to improve the validity of a test by improving its reliability.

## What does 0 discrimination index mean?

If an item has a discrimination index of 0, it indicates **it is not discriminating at all** – i.e. the same number of people in the higher group got it correct as in the lower group. Whether that is an issue will depend both on the type of item and what proportion of candidates overall got it correct (the mean).

## What is the difference between difficulty index and discrimination index?

Item difficulty is the percentage of learners who answered an item correctly and ranges from **0.0 to 1.0**. The closer the difficulty of an item approaches to zero, the more difficult that item is. The discrimination index of an item is the ability to distinguish high and low scoring learners.

## What is discrimination formula?

Discriminant, in mathematics, a parameter of an object or system calculated as an aid to its classification or solution. In the case of a quadratic equation ax^{2} + bx + c = 0, the discriminant is b^{2} − 4ac; for a cubic equation x^{3} + ax^{2} + bx + c = 0, the discriminant is a** ^{2}b^{2} + 18abc − 4b^{3} − 4a^{3}c − 27c^{2}**.

## What does the test mean if the difficulty index is 1?

For example, if a given item has a discrimination index below . 1, but the item’s p-value is greater than . 9, you may **interpret the item as being easy for almost the entire set of examinees**, and probably for that reason not providing much discrimination between high ability and low ability examinees.

## How do you determine the difficulty level of a test item?

Calculating Item Difficulty

Count **the total number of students answering each item correctly**. For each item, divide the number answering correctly by the total number of students. This gives you the proportion of students who answered each item correctly. This figure is called the item’s difficulty level.

## What is reliability index?

Item reliability index is **equal to the product of the discrimination and standard deviation of the item**. So item realibility index=r_{jx}.S_{x}. This index can be calculated for dichotomous or polytomous item type.

## What is the difference between item discrimination and item difficulty?

So item difficulty helps us to know the degree to which students get answers correct, whereas item discrimination **examines how the top-scoring group of test takers compares to the lowest-scoring group of test takers**, another important piece of information to help us know how well our items are working.

## What is positive discrimination index?

A positive discrimination index indicates that **those students who got the test item correct also had a high overall exam score**. When the discrimination index is negative it means that the examinees in the low performing group got the answer correct at a higher rate than the higher performing group.

## What is Miskeyed item?

(ˌmɪsˈkiː) vb (tr) to key (something) incorrectly on **a keyboard**.