Validity And Reliabilty


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Validity And Reliabilty

  1. 1. This presentation was developed for the exclusive use of students enrolled in: Educational Testing & Grading, Professor Gregory E. Stone. © 2004 Gregory E. Stone. All rights reserved. This presentation may not be reproduced in any form, in part or as a whole, without the express written permission of the author.
  2. 2. Exam Score Quality Validity & Reliability
  3. 3. No matter how well the objectives are written, or how clever the items, the quality and usefulness of an examination is predicated on Validity and Reliability Validity & Reliability
  4. 4. Evaluative Examination Score Quality Statistical Validity & Reliability
  5. 5. Validity Examination Score Quality Reliability Validity & Reliability
  6. 6. Validity BOTH CONCEPTS RELATE TO THE SCORE NOT THE TEST! Reliability Validity & Reliability
  7. 7. Validity Reliability We don’t say “an exam is valid and reliable” We do say “the exam score is reliable and Valid for a specified purpose” KEY ELEMENT! Validity & Reliability
  8. 8. Reliability “Was the measure of student ability reached by accident or chance, or was it reached through a clear and stable, meaningful examination?” Validity & Reliability
  9. 9. Reliability Answers questions relative to the stability and clarity of an examination. Validity & Reliability
  10. 10. Reliability Reliability is a STATISTIC. Specifically, a correlation ranging from 0 = Completely Unreliable 1 = Perfectly Reliable Validity & Reliability
  11. 11. Reliability Reliability is also a measure of error within an examination. Poor wording, ambiguity, correct answer issues, failure to link with objectives, etc. Validity & Reliability
  12. 12. Content/ Action + Error Validity & Reliability
  13. 13. The information we seek and our best hope for obtaining it. Content/ Action + Error Validity & Reliability
  14. 14. The information we seek and our best hope for obtaining it. Content/ Action + Error Our human frailty and inability to write effective questions. Validity & Reliability
  15. 15. Reliability Reliability comes in multiple forms, including: Test-Retest Reliability Split-Half Reliability Validity & Reliability
  16. 16. Reliability Test-Restest Administer to students. After time, administer again. Are the students performing in a consistent manner? Validity & Reliability
  17. 17. Reliability Split-Half Create 2 smaller content Balanced tests and administer. Do students perform similarly on each test half? Validity & Reliability
  18. 18. Validity “Did the test we created really measure what we hoped it would measure?” Validity & Reliability
  19. 19. Validity Relates to questions about the reasonability of content, criterion and construct associated with the learning objectives and assessment. Validity & Reliability
  20. 20. Validity & Reliability
  21. 21. Validity & Reliability
  22. 22. Validity Content Related Validity Does the content we have selected appropriately represent our construct (top level domain)? Validity & Reliability
  23. 23. Validity Construct Validity Is there really such a concept as what we created as a construct? (e.g. Does “reading ability” really exist?) Validity & Reliability
  24. 24. Validity Criterion Related Validity Does our test adequately link the content to the construct? Is the test a good measure of the construct? Validity & Reliability
  25. 25. Validity Examination Quality Reliability Validity & Reliability
  26. 26. Validity & Reliability
  27. 27. RELIABILITY is a necessary but not sufficient condition for VALIDITY Validity & Reliability