Validity of Alternative Approaches to the Identification of LD: Operationalizing Unexpected Underach

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Validity of Alternative Approaches to the
Identification of LD Operationalizing
Unexpected Underachievement

• Jack M. Fletcher, Ph.D. Carolyn Denton
• U of Texas- Houston U of Texas- Austin
• CARS.uth.tmc.edu
• Jack.Fletcher_at_uth.tmc.edu

Responsiveness-to-Intervention Symposium December
4-5, 2003 Kansas City, Missouri The National
Research Center on Learning Disabilities, a
collaborative project of staff at Vanderbilt
University and the University of Kansas,
sponsored this two-day symposium focusing on
responsiveness-to-intervention (RTI) issues. The
symposium was made possible by the support of the
U.S. Department of Education Office of Special
Education Programs. Renee Bradley, Project
Officer. Opinions expressed herein are those of
the authors and do not necessarily represent the
position of the U.S. Department of
Education. When citing materials presented
during the symposium, please use the following
Fletcher, J. M., Denton, C. (2003, December).
Validity of alternative approaches to the
identification of LD Operationalizing unexpected
underachievement. Paper presented at the National
Research Center on Learning Disabilities
Responsiveness-to-Intervention Symposium, Kansas
City, MO.
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Learning Disabilities is a Construct

• Essential aspect of construct is unexpected
  underachievement
• Constructs do not exist independently of how they
  are measured all measures are imperfect
  indicators of constructs (latent variables)
• Measurement depends on definition
• Definitions and the resultant identification
  criteria derive from classifications
• All classifications are hypotheses that must be
  tested

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Learning Disabilities is a Construct

• Does the identification model that is derived
  from the classification identify a unique
  subgroup of underachievers?
• Children may be validly identified even when the
  underlying classification does not yield a unique
  subgroup is the classification valid?
• Validity of classifications only be tested on
  variables not used to form the classification-
  cognitive skills, response to intervention,
  neuroimaging, genetics
• Validity assumes reliability

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LD is a Valid Classification

• Learning disabilities are real! Stands up across
  definitional variation (doesnt help identify
  individuals)
• Children and adults with different forms of
  LD can be reliably and validly differentiated
  from each other, typical achievers, and other
  disabilities on cognitive correlates, response to
  intervention, neural correlates, and heritability
• What happens when we apply these criteria to
  different classifications?

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Alternative Classification Models

• 1. Different forms of discrepancy VIQ, PIQ,
  Listening comprehension- reading comprehension
• 2. Low achievement
• 3. Intra- individual differences
• 4. Response to intervention
• 5. Hybrid models

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Alternative Discrepancy Models Discrepant vs.
LA(Fletcher et al., 1994)
80 impaired under all definitions difference is
in people above the low achievement cut point,
but below the regression cut point
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Low Achievement

• Designate a cut point on the achievement
  dimension
• Strengths Strong validity, linked to
  intervention, easy to implement
• Weaknesses Cut point, does not measure the
  underlying construct (cant differentiate
  subgroups of poor readers when the cause is known
  to be related to emotional difficulty, economic
  disadvantage, and inadequate instruction)
• Necessary but not sufficient

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Intra- Individual Differences Model

• while IQ tests do not measure or predict a
  students response to instruction, measures of
  neuropsychological functioning and information
  processing could be included in evaluation
  protocols in ways that document the areas of
  strength and vulnerability needed to make
  informed decisions about eligibility for
  services, or more importantly, what services are
  needed.

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Intra- Individual Differences Model

• An essential characteristic of SLD is
  failure to achieve at a level of expected
  performance based upon the students other
  abilities (NCLD, 2002, p. 4).
• Another version of a 2 test (or more)
  discrepancy?

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Biobehavioral Systems Model
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Problems

• Processing subtypes, patterns weakly related to
  intervention outcomes (if at all)
• Not sure of what processes to measure outside
  word recognition
• What about non- MR children with flatter
  profiles? (Biased towards milder impairments
  because severity is correlated with shape)
• Perpetuates assessment model (test and treat)
  that has not been effective in enhancing outcomes
• Difficult to scale (send all school psychologists
  to NP school?)
• But strong validity at achievement level (What
  information is added outside variation in
  achievement domains?)

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Response to Intervention

• Serial curriculum- based assessments of learning
  in relation to an intervention
• Identification is more reliable than when based
  on a single assessment, even if the intercept is
  used
• As one criterion, student may be LD if they do
  not respond to instruction that works with most
  other students (I.e., unexpected
  underachievement)
• Identifies a unique subgroup of underachievers
  that reflects an underlying classification that
  can be validated (Al- Otaiba Fuchs, 2002
  Vellutino et al., 2003)

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What percentage of G1 children dont respond
adequately to quality intervention?(Mathes et
al., 2003)

• Primary only 14/90 16 (3 of school
• population)
• Primary Secondary
  
• Proactive 1/82 lt 1 (lt .2 of school
  population)
• Responsive 7/83 8 (lt1.5 of school
  population)
• (Woodcock Basic Reading lt 30th percentile)

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Severe RD before and after 8 week intervention
(7- 17 years old) Simos et al. (2002)
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Not At Risk
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At Risk Responders
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At Risk Nonresponders
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What about the Nonresponders (Grade 2 and 3)?
Wave 1 Wave 2
Wave 3 Wave 4 Round 1
Phono-Graphix Read Naturally     8 weeks
8 weeks 8 weeks     Round 2
Baseline Phono-Graphix Read
Naturally       8 weeks 8 weeks
8 weeks
 
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Woodcock-Johnson III Basic Skills Standard Scores
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Gray Oral Reading Test Fluency Standard Scores
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Gray Oral Reading Test Comprehension
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Problems

• What is the best cut point? (index to benchmarks,
  growth, norm referenced scores probably makes
  little difference if measurement error taken into
  account dont make it a formula)
• Scaling and implementation problem is not with
  the research base, but with its scaling (so what
  else is new? 30 years later we still cant do IQ
  discrepancy correctly)
• Necessary but not sufficient needs additional
  criteria

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OSEP LD Summit Hybrid Model

• 1. Low Achievement
• 2. Apply the Exclusions
• 3. Evaluate Response to Intervention
• (maintain flexibility of the interdisciplinary
  team)
• Unlike other alternative models, may yield a
  valid classification of unexpected underachievers