Assessment Interpretation: Predicted Achievement/Achievement Discrepancy Procedure

Posted on January 01, 2012

In discrepancy analysis, assessing the student with co-normed cognitive and achievement batteries holds many advantages, as opposed to using one brand of cognitive and another of achievement. Co-normed data represents true discrepancies, while different branded data must be statistically estimated.

The Predicted Achievement/Achievement Discrepancy Procedure is designed to predict a student’s learning potential in a narrow achievement area for the near term. It is not designed to predict achievement over time. This discrepancy procedure can help educators to understand if students are performing as expected, given their individual performance on relevant cognitive abilities, and if learning in that achievement area can be reasonably accelerated (with accommodations). Predicted scores:

  • Are the strongest predictor of achievement in the near term.
  • Can predict achievement in reading, mathematics, written language, oral language, and knowledge.
  • Are based on differential weighting of WJ III cognitive tests 1-7, specific to one narrow achievement area and specific to the student’s age.
  • Can provide valuable insight into accommodations and strategies to assist non-responders to RtI/MTSS.
  • Will generate predicted discrepancies only if Cognitive Tests 1-7, AND Achievement Cluster scores are administered.
  • Are discrepancies that are automatically generated and included in Compuscore results.












Predicted Achievement: Basic Reading Skills

(Based on COG Tests 1-7) Listed in order of importance from most to least at each age

Basic Psychological Processes:

CK = Comprehension Knowledge ( Subtest #1, Visual-Auditory Learning)

LTR = Long Term Retrieval (Subtest #2, Visual-Auditory Learning)

VS = Visual-Spatial Learning (Subtest #3, Spatial Relations)

AP = Auditory Processing (Subtest #4, Sound Blending)

FR = Fluid Reasoning (Subtest #5, Concept Formation)

PS = Processing Speed (Subtest #6, Visual Matching)

STM = Short-Term Memory (Subtest #7, Numbers Reversed)


In the example above, the Actual score represents the student’s standard score obtained for that achievement cluster. The Predicted score is a weighted standard score from cognitive subtests 1-7, for that student’s age +- 1 month. The Difference score is the number of standard score points between the actual and predicted, higher or lower. The discrepancy PR is the percentile rank of students the same age as the subject student, who evidenced a similar discrepancy in the norming sample. The SD column represents the standard deviation discrepancy between the predicted and actual scores. The Significance column indicates whether the discrepancy is statistically significant at the 1.5 sd level. Note that both negative discrepancies (student is performing lower than predicted level) and positive discrepancies (student is performing higher than expected) are represented.

A significant (negative) discrepancy between potential and actual scores suggests that the student has the potential to perform at a significantly higher level than current performance. The larger the discrepancy, the greater potential for rapid growth. Assuming that the student has already received quality Tier 1, 2 and even 3 interventions, specialized instruction is indicated. Practitioners need to analyze the student’s cognitive factor scores, looking for one or more basic psychological processes that is significantly lower than others, that is highly correlated with the specific achievement area of concern.

A positive predicted discrepancy suggests that the student is performing above a predicted level. Often, this can be attributed to extra tutoring, an above-average level of homework support at home, or in an extra rigorous teaching environment where that achievement area is given extra time or special treatment.

Author: Michael Herbert, Program Specialist, Utah Personnel Development Center (UPDC)