1. Reliability is when test scores are consistent over a number of attempts by the same person.
1.1. Test-Retest or Stability- The test is given twice and a correlation is determined between the first and second set of scores.
1.2. Alternate Forms or Equivalence- If there are two equivalent forms of a test, these forms can be used to obtain an estimate of the reliability of the scores from the test.
1.3. Internal consistency- If the test in question is designed to measure a single basic concept, it is reasonable to assume that people who get one item right will likely get another, like-item right.
2. Validity is when a test measures what it is supposed to measure.
2.1. Content Validity- inspects test questions to see whether they correspond to what the user decides should be covered by the test.
2.2. Criterion-Related Validity-scores from the test are correlated with an external criterion. Concurrent and Predictive.
2.3. Construct Validity Evidence- relationship to other information must correspond well with some theory.
3. These are both important because both make sure our educational assessments are actual and true. Without valid or reliable assessments, we might as well not assess our students at all.
