The difficulty index measures the difficulty associated with a given task. The task can be a test associated with an educational course, training program or a work-related task. This is why the index is used by teachers, professionals, trainers and corporate managers. The index is between 0 and 1 and presented in the form of a percentage.

### Step 1

Determine what constitutes a successful result of the exercise or task you are looking to evaluate. As a simple example, assume you are looking to measure the difficulty index of a test administered in a classroom where 70 percent is a passing grade.

### Step 2

Record the number of people participating in the exercise. In our example, assume 20 students will take the test.

### Step 3

Record the number of people who completed the exercise successfully. In our example, assume 13 students pass the test.

### Step 4

Calculate the difficulty index by dividing the number of people who completed the task successfully by the number of people participating in the task. In our example, this is 13/20 which 0.65 or 65 percent. The difficulty index for this example is 65 percent.

### Step 5

The difficulty index can also apply to a specific question, rather than the entire test. You can assess whether a question may be too difficult or too easy by looking at the percentage of students who answered correctly. A test question that doesn't challenge students to think isn't useful in measuring learning, and should be removed.