How can one improve the reliability of a test?

Increasing the number of test items can significantly improve the reliability of a test. Reliability refers to the consistency and stability of test results over time. When more test items are included, it generally leads to a more comprehensive assessment of the construct being measured. This enhanced coverage helps to minimize the impact of any single item on the overall score, thereby providing a clearer and more stable indication of a person's abilities or knowledge.

With a larger number of items, the influence of random error is reduced, since it is less likely that a person's performance will be swayed by a few anomalous questions. A test that includes various items taps into different aspects of the construct, allowing for a better estimation of the true ability of the test-taker. This contributes to higher reliability coefficients, which reflect more consistent results across different administrations of the test.

In contrast, the other options do not fundamentally enhance the reliability of a test in the same way. Limiting training for administrators may actually introduce inconsistencies, while ensuring a variety of difficulty levels could complicate the interpretation of results. Finally, reducing the time allowed for completion might lead to increased stress and lower performance, which could further diminish reliability.