validity and reliability

1. Validity refers to the accuracy of score-based inferences—by giving approbation to consequential validity.

2. Three Types of Validity

2.1. Construct Validity Evidence

2.1.1. Intervention Studies

2.1.2. Differential-Population Studies

2.1.3. Related-Measures Studies

2.2. Content Evidence refers to the adequacy with which the content of a test represents the content of the curricular aim about which inferences are to be made.

2.3. Criterion-Related Evidence this kind of evidence helps educators decide how much confidence can be placed in a score-based inference about a student’s status with respect to one or more curricular aims.

3. Three types or reliability

3.1. "stability reliability" reliabilty = consistency Test and Retest

3.2. "Alternative form or Equivalence" Form Consistency of results among two or more different forms of a test

3.3. "Internal Consistency" Consistency in the way an assessment instrument’s items function

4. Why you need reliability? You need reliability because you may be called on to explain to parents the meaning of a student’s important test scores, and you’ll want to know how reliable such tests are. You need to know what the test manual’s authors are talking about and to be wary of those who secure one type of reliability evidence. Also to ensure your teaching assessments are actually teaching your students and helping them to become successful.