A. 30-70 %
B. 70 %
C. 30%
D. None
Answer is =A
You are absolutely right! A test item is generally considered acceptable if its facility index (difficulty level) falls within a range of:
A. 30-70%
Here’s why this range is preferred:
- Provides a good spread of difficulty: Having items with varying difficulty levels helps to assess a wider range of knowledge and abilities among test-takers. It allows for discrimination between high and low achievers and caters to students with different learning paces.
- Minimizes guessing: If all the items are extremely difficult (low facility index), students are more likely to resort to guessing, which can lead to unreliable scores. Conversely, very easy items (high facility index) don’t effectively differentiate between those who understand the concept and those who may have guessed correctly.
It’s important to note that the ideal range for the facility index can vary depending on the specific test and its purpose. Here are some additional considerations:
- Formative vs. summative assessments: Formative assessments used for providing feedback during learning might have a wider range of difficulty levels to identify areas where students need more support. Summative assessments used for measuring overall achievement might target a narrower range closer to the expected learning level.
- Criterion-referenced vs. norm-referenced tests: Criterion-referenced tests compare student performance to a specific learning objective, and the facility index might be tailored accordingly. Norm-referenced tests compare students to a peer group, and the desired range might be adjusted to achieve a normal distribution of scores.
In conclusion, a facility index between 30-70% is generally considered a good rule of thumb for test items. This range promotes a good balance of difficulty, allowing for effective assessment and differentiation between students with varying levels of knowledge or skill.