Validity

• Assessments must be created for specific educational objectives. Validity is the degree to which the particular assessment measures those objectives. There are three major types of validity present in classroom testing situations: content, criterion and construct validity. Content validity is achieved when the content of the assessment matches the educational objectives. Criterion validity is demonstrated by the ability of the test to relate to external requirements, as in a proficiency exam. Construct validity takes into account the educational variables, such as the native language of the students, to predict the test outcomes.
  
  

Reliability

• Reliable assessments have consistent results. Classroom tests require three main reliability measures: stability, alternate form and internal consistency. The stability of the test can be measured by administering the same assessment twice with some separation of time. Similar results show high reliability, whereas different results show low reliability. Alternate form reliability is measured by creating multiple forms of the test using the same information. Similar results on the alternate forms indicate high reliability. Internal consistency compares halves of the assessment using formulas such as Cronbach's Alpha.
  
  

Achieving Validity and Reliability

• First, you must decide and clarify what is expected of the students. If you are not measuring something specific, the test cannot be valid. After clarifying expectations, compare them to the test. Other opinions are helpful when evaluating your assessments -- having another person make this comparison can improve your results. Second, run your test through at least one or two of the measures of reliability. Once again, enlisting the help of coworkers increases your chance of unbiased feedback.
  
  

Classroom Implications

• Testing with purpose, using assessments that are both valid and reliable, can have positive results in the classroom. Ideally, the assessment reflects the most important skills and information to be learned. Creating a valid assessment before beginning to teach the unit ensures that the lesson plans will focus on the most essential elements of the educational objectives. Student learning is enhanced by understanding the importance and life application of the subject, both of which can be underlined during the unit when working toward the culminating assessment.