What could affect reliability?

There are several factors that can affect the reliability of an assessment. You may find yourself needing to explain the results of a test to different stakeholders.

Consider the following factors and how they might impact reliability. 

Test items

  • Different tasks, questions, or prompts can be intended to measure the same knowledge or skill
  • Do different items produce consistent results when testing for the same skill? 

Test administration

  • Testing environment, administration, location, time of day, available materials
  • Is a test given to one group of students on one day consistent with the results produced from the same group on a different day?


  • Guidelines for assessing student performance on a test: Rating is an example of a type of scoring that requires a human rater and qualitative, descriptive terms to designate different levels of performance.
  • Are test results consistent under a trained rater? Are results consistent among different, trained raters?