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


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

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

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.
Learning Disabilities is a Construct
  • Essential aspect of construct is unexpected
  • 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

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

LD is a Valid Classification
  • Learning disabilities are real! Stands up across
    definitional variation (doesnt help identify
  • 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?

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

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
(No Transcript)
Low Achievement
  • Designate a cut point on the achievement
  • 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

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

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)

Biobehavioral Systems Model
  • 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?)

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
  • As one criterion, student may be LD if they do
    not respond to instruction that works with most
    other students (I.e., unexpected
  • Identifies a unique subgroup of underachievers
    that reflects an underlying classification that
    can be validated (Al- Otaiba Fuchs, 2002
    Vellutino et al., 2003)

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
  • Responsive 7/83 8 (lt1.5 of school
  • (Woodcock Basic Reading lt 30th percentile)

Severe RD before and after 8 week intervention
(7- 17 years old) Simos et al. (2002)
Not At Risk
At Risk Responders
At Risk Nonresponders
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
Woodcock-Johnson III Basic Skills Standard Scores
Gray Oral Reading Test Fluency Standard Scores
Gray Oral Reading Test Comprehension
(No Transcript)
  • 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

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