Assessment: Reliability & Validity

Reliability Refers to the repeatability of a given testing instrument The extent to which a student would be expected to perform similarly across multiple administrations of the test under similar conditions A test given today should produce, approximately, the same score if given tomorrow Assuming that no intervention has occurred

Types of Reliability Test-retest reliability. A method for assessing the reliability of an instrument by administering the same test at different points in time. The correlation between the 2 should be high. Alternate forms reliability. Refers to the relationship between scores on alternative forms of the same test, given closely in time. In the case of pre-post testing, alternate forms reliability is more important than test-retest.

Validity Refers to the extent to which a given test is measuring what it is expected to measure Ex. If a question is wrong on a math test because student couldn’t read the word problem, but s/he could do the math in the question, then the question is also measuring reading ability, not just math ability. The question, therefore, may not be a valid indicator of the student’s math ability.

Types of Validity Construct validity. Refers to evidence that a test is measuring the content & skills (or construct) it claims to measure. 2 common types: convergent validity: the extent to which the scores on a given test are related to scores on other tests designed to measure the same, or very similar, constructs discriminant validity: the extent to which the scores on a given test are related to scores on tests designed to measure something different.

Types of Validity Content validity. The extent to which the items/tasks adequately cover the area of interest. For ex.: in a test on reading comprehension, all of the items/tasks should: align w/the skills associated w/reading comprehension, and represent the full range of skills associated w/reading comprehension. Skills not associated w/this area, such as knowledge of science or social studies, should not influence performance External validity. The extent to which the results of a test given to one population of students are relevant to other groups of students. For ex.: test norms based on data collected from students enrolled in traditional classrooms may not be as useful for gauging the progress of students in alternative types of educational programs, especially w/respect to factors such as socioeconomic status & age

Works Cited National Education & Technical Assistance Center for the Education of Children & Youth who are Neglected, Delinquent, & At-Risk. A brief guide to selecting & using pre-post assessments. April, Found online at delinquent.org/nd/resources/spotlight/spotlight a.asphttp:// delinquent.org/nd/resources/spotlight/spotlight a.asp