Examining Test Items for Differential Distractor Functioning Among Students with Learning Disabiliti...
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Examining Test Items for Differential Distractor Functioning Among Students with Learning Disabilities. Kyndra Middleton The University of Iowa [email protected] April 10, 2007. Purpose of the Study.

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Kyndra Middleton The University of Iowa [email protected] April 10, 2007

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Kyndra middleton the university of iowa kyndra middleton uiowa april 10 2007

Examining Test Items for Differential Distractor Functioning Among Students with Learning Disabilities

Kyndra Middleton

The University of Iowa

[email protected]

April 10, 2007


Purpose of the study

Purpose of the Study

  • To examine whether different distractor choices functioned differentially for students with learning disabilities who did not receive an accommodation, students with learning disabilities who received a read-aloud accommodation, and students with learning disabilities who received an accommodation other than a read-aloud

  • To help determine whether a test can be modified for students with learning disabilities by removing a distractor choice while maintaining adequate test validity and information


Instrument used

Instrument Used

  • 4th grade English Language Arts assessment from a criterion-referenced statewide test

    • Operational test data

    • Reading (42 MC items)

    • Writing (33 MC items)


Sample used

Sample Used

  • 30,000 non-LD students sampled from 298,622 students

  • 9,056 LD students who did not receive an accommodation

  • 4,727 LD students who received an accommodation based on their IEP/504 plan

  • 1,371 LD students who received an accommodation based on their IEP/504 plus a read aloud accommodation


Sample used cont d

Sample Used cont’d

Percentage of Students at Each Proficiency Level


Sample used cont d1

Reference-Focal Comparisons

Sample Used cont’d

Note: IEP = Individualized Education Plan

* = comparison did not show DIF so was not included in the DDF analyses


Procedure

Procedure

  • Examine items that previously displayed DIF for DDF

    • DDF: when two groups that have been matched on ability have different probabilities of selecting a distractor

  • Standardized Distractor Analysis (SDA)

    • Distinguishes between distractors

    • Identifies uniformly and nonuniformly biased distractors

    • An extension of standardized p-difference


Procedure used cont d

Procedure Used cont’d

  • Equation used to test for DDF:

    STD(i) =

  • : negligible DDF

  • : moderate DDF

  • : large DDF


Results

Results

  • 70% of the items that displayed DIF also displayed DDF

  • 100% of DDF occurred with a comparison between the read aloud and some other group

  • 64% of the distractors that displayed DDF were in favor of the read aloud group


Results cont d

Results cont’d

Note: +: moderate DDF in favor of the focal group

++: large DDF in favor of the focal group

-: moderate DDF in favor of the reference group

*R: DIF in favor of the reference group

*F: DIF in favor of the focal group

Shaded box: Items that did not exhibit DIF


Results cont d1

Results cont’d

  • 17% that assessed reading standards showed DDF

  • 9% that assessed writing standards showed DDF

  • No observed pattern across content or cognitive area between groups


Results cont d2

Results cont’d

  • Item that displayed large DDF was the most difficult item that displayed DIF

  • One item displayed DDF in each of the distractors (two favoring the read aloud group and one favoring the non-LD group)

  • Item that displayed DDF in two of its distractors was a spelling item

    • Both were homophones

    • Additional difficulty caused by read aloud


Conclusions future research

Conclusions/Future Research

  • Measurement dissimilarity between read aloud group and other groups

  • Exploratory study: More research needed to determine whether read aloud actually alters test’s validity

  • Matched on ability to provide more information at extremes


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