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Using Item Response Theory to Track Longitudinal Course Changes

Using Item Response Theory to Track Longitudinal Course Changes. Charles H. Atwood, Braden Ohlsen , and Brock Casselman University of Utah Department of Chemistry Salt Lake City, UT. Quick Description of Item Response Theory (IRT). Classical Test Theory (CTT) Mean, median, mode

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Using Item Response Theory to Track Longitudinal Course Changes

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  1. Using Item Response Theory to Track LongitudinalCourse Changes Charles H. Atwood, Braden Ohlsen, and Brock Casselman University of Utah Department of Chemistry Salt Lake City, UT

  2. Quick Description of Item Response Theory (IRT) • Classical Test Theory (CTT) • Mean, median, mode • Discrimination Index • comparison of top and bottom quartiles • CTT is good for small samples • CTT is more dependent upon the subject group • Same assessment given to 2 groups will give different results

  3. Quick Description of Item Response Theory (IRT) • Item Response Theory (IRT) • More modern psychometric analysis tool than CTT • Works well for large sample sizes (> 200) • Iterative process which fits the students responses to a mathematical formula

  4. Quick Description of Item Response Theory (IRT) • We use the program Bilog-MG3 to fit our data. • Bilog-MG3 assigns to every test item values for a, b, and c and displays them on an item characteristic curve • Plot of the probability of a student with a given IRT ability vs. probability that the student answered the question

  5. Quick Description of Item Response Theory (IRT) • Item Characteristic Curve

  6. Description of Item Response Theory (IRT) • Item Information Curve for every test question

  7. Description of Item Response Theory (IRT) • Test information curve • Sum of Item Information Curves for an assessment

  8. IRT Equating

  9. CHEM 1210Equated Average Scores2014 - 2016

  10. Equated Test 1

  11. Equated Test 2

  12. Equated Test 3

  13. ACS FINAL EXAMCHANGES FROM 2013 TO 2016

  14. CHEM 1220Equated Average Scores2015 - 2016

  15. Equated Test 1

  16. Equated Test 2

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