1 / 10

LECTURE 14 NORMS, SCORES, AND EQUATING

LECTURE 14 NORMS, SCORES, AND EQUATING. EPSY 625. NORMS. Norm: sample of population Intent: representative of population Reality: hope to mirror population characteristics (no means to get representative samples, except NAEP). NORMS. Norming study Construct test Pilot items

zia-talley
Download Presentation

LECTURE 14 NORMS, SCORES, AND EQUATING

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LECTURE 14NORMS, SCORES, AND EQUATING EPSY 625

  2. NORMS • Norm: sample of population • Intent: representative of population • Reality: hope to mirror population characteristics (no means to get representative samples, except NAEP)

  3. NORMS • Norming study • Construct test • Pilot items • Construct test(s) • Testlets/item packets • Parallel forms • Revise items/tests • Test norm sample

  4. Test Scores • Types of scores • Smoothing distributions • Equating scores for different forms • horizontal (same difficulty/population) • vertical (different difficulty/population)

  5. Types of scores • Raw scores • Standardized scores • linear transformations of raw scores • z-scores (mean=0, SD=1) • T-scores (mean=50, SD=10) • Stanines (mean=5, SD=2) • nonlinear transformations of raw scores • percentile scores • smoothed standard scores • grade equivalents (GEs)

  6. RAW SCORE SAMPLE C GRADE 2 18 15 12 9 6 3 0 SAMPLE A GRADE 1 SAMPLE B GRADES 1-2 1.1 1.5 1.9 2.1 2.5 2.9 TIME OF TESTING IN GRADE UNITS

  7. Smoothing Distributions • Normal curve fitting • trait-theoretic (ability, physical performance) • Nonnormal curve fitting • trait theoretic (abnormal behavior) • Procedures • graphical fitting • mathematical curve-fitting

  8. Test Equating Horizontal equating: parallel forms Equipercentile: match scores for each percentile score (eg. 1%ile on form A to 1%ile on B) IRT ability equating (mean score for ability value of -.5 on A to mean score on B) Regression/linear procedures Vertical equating: overlapping difficulties IRT ability equating Grade equivalent equating

  9. Test Equating Horizontal equating: parallel forms Equipercentile: match scores for each percentile score (eg. 1%ile on form A to 1%ile on B) FORM A FORM B 75 99 73 98 70 97 66 96 65 95 . . 99 76 98 74 97 71 96 67 95 66 . .

  10. Test Equating • Vertical equating: overlapping difficulties • Scores are overpredicted based on easy forms • Scores are underpredicted based on difficult forms • Chance scores are overpredicted

More Related