Understanding Comparison Base-Rate Procedures in the WJ V: Case Studies for Practice

What are Comparison Base-Rate Procedures?

Comparison base-rate procedures allow an examiner to compare a student’s performances within and between administered test batteries. Each comparison base-rate procedure calculates the difference between a student’s attained cluster score and the student’s score on a predictor cluster or pooled set of tests. The resulting scores include a standard score difference, which reflects the difference between the attained and predicted scores as well as the direction of the difference. Additionally, the base rate of the examinee’s difference score, which tells us how unexpected the examinee’s earned target cluster score is, given the student’s performance on the predictor cluster or set of tests.

There are two categories of comparison base-rate procedures, each of which uses a different predictor score. The first category, Intra-Ability comparison base rate procedures, includes three types: Intra-Cognitive, Intra-Achievement, and Academic Skills/Fluency/Applications. The table below indicates which WJ V tests must be administered in order to calculate the predictor score. Once the tests making up the predictor score have been administered, intra-ability comparison base rate scores are available for any of the target administrated clusters.

The second category of comparison base-rate procedures is Ability/Achievement. This category includes four types: General Intellectual Ability (GIA)/Achievement, Oral Language Ability/Achievement, Academic Knowledge/Achievement, and Gf-Gc Composite/Other Abilities. The table below indicates which WJ V cluster score is required as the predictor score. Once that predictor score is administered, ability/achievement comparison base rate scores are available for any of the target clusters that have been administered.

Each case scenario below highlights how examiners can use the WJ V’s comparison base-rate procedures to easily interpret a student’s personal strengths, and areas that may warrant intervention.

WJ V ACH Intra-Ability Comparison Base Rate Procedure: Sarah & Math

Intra-Achievement

Notes. The predictor for each target cluster score is the average of the examinee's earned standard scores from the following six tests: Letter-Word Identification, Passage Comprehension, Spelling, Written Language Samples, Calculation, and Applied Problems.

Sarah is a fifth-grade student who was referred for a private academic screening assessment due to concerns from her mother regarding her math skills. She currently is in a general education classroom and receives supplementary instruction from a special education teacher to improve her math calculation skills. Despite this additional support, she continues to struggle in comparison to her classmates.

As part of the evaluation, a private psychologist administers the 6 tests of the WJ V ACH required for the Intra-Achievement comparison base-rate procedure (Letter-Word Identification, Passage Comprehension, Spelling, Written Language Samples, Calculation, and Applied Problems) in addition to the math tests that make up the Math Problem Solving and Math Calculation Skills clusters of the WJ V ACH: Applied Problems, Math Problem Identification, Calculation, and Math Facts Fluency.

Administering these tests allows the psychologist to obtain a profile of Sarah’s academic strengths and weaknesses through the intra-achievement base-rate comparison procedures. Based on the above data, the psychologist finds that Sarah has a significant intra-achievement base rate comparison in Math Problem Solving.

Math Problem Solving Interpretation: Sarah’s actual mathematics problem-solving skills were found to be more than two standard deviations below expectations, based on her performance across other areas of achievement. Moreover, the difference between her actual and expected performance on Math Problem Solving is only observed in 1% of her age-peers. The psychologist interprets this to mean that Sarah performed well below expected levels, and that the observed difference is quite rare when compared to her age-peers.

Math Calculation Skills Interpretation: Using these data, the psychologist also determines that Sarah’s performance on measures of her of mathematical operations knowledge was approximately 0.80 standard deviations above expectations. The psychologist surmises that this is likely in response to Sarah’s participation in supplementary instruction that targets her calculation skills.

Considering these findings, the psychologist recommends further assessment in the domain of Fluid Reasoning, using the WJ V COG. The psychologist explains that Fluid Reasoning is predictive of performance in applied problem solving. By administering this domains, the psychologist can compare Sarah’s cognitive functioning to the identified weaknesses in academic achievement.

Sarah’s mother agrees to further testing. The psychologist also recommends that Sarah’s school shift Sarah’s supplementary math instruction to target her problem-solving skills, as her calculation skills were found to be almost one standard deviation above expected levels.

*These data are completely fictional and are solely provided for illustrative purposes.

WJ V COG Intra-Ability Comparison Base Rate Procedure: Jacob & Memory

Intra-Cognitive

Notes. The predictor for each target cluster score is the average of the examinee's earned standard scores from the following eight tests: Oral Vocabulary, Matrices, Spatial Relations, Story Recall, Semantic Word Retrieval, Verbal Attention, Number-Pattern Matching, and Verbal Analogies. The difference score significance is based on ±1.50 SD (SEE).

Jacob is a 21-year-old college student who self-referred for a private neuropsychological evaluation after suffering a traumatic brain injury during a car accident. He currently sees both a generalist and neurologist for ongoing medical treatment. He reports concerns with following complex (multi-step) directions and recalling information from conversations. As part of the evaluation the neuropsychologist administers the 8 tests of the WJ IV COG required for the Intra-Cognitive comparison base-rate procedure (Oral Vocabulary, Matrices, Spatial Relations, Story Recall, Semantic Word Retrieval, Verbal Attention, Number-Pattern Matching, and Verbal Analogies) in addition to the remaining tests needed to derive the Auditory Working Memory Capacity (Numbers Reversed), Long-Term Storage (Story Comprehension), and Retrieval Fluency (Phonemic Word Retrieval) clusters.

Based on the above data, the neuropsychologist finds that Jacob has two significant intra-cognitive variations in Auditory Working Memory and Retrieval Fluency.

Auditory Working Memory Interpretation: Jacob’s ability to hold and manipulate information in his immediate awareness, while honing his attention, tested approximately -1.6 standard deviations below expectations. The magnitude of the negative difference between Jacob’s actual and predicted Auditory Working Memory score is rare, as it is only observed in 5% of those his same age.

Retrieval Fluency Interpretation: Jacob’s ability to access information stored in long-term memory also tested lower than expected. His observed performance fell approximately 1.89 SDs below expected levels and the magnitude of difference between Jacob’s actual and predicted Retrieval Fluency score is rare, only observed in 3% of those his same age.

The neuropsychologist explains that short-term working memory is needed to hold information, such as directions, long enough in mind for it to be processed, and shares that this ability was found to be weaknesses in his profile.

The neuropsychologist further shares that Jacob’s access to his long-term memory was found to be particularly underdeveloped based on expectations set by his performances in other cognitive domains. They express that this is what we use to remember contextualized verbal information, such as data gathered through informal conversations and classroom lessons. These data are validating to Jacob, who was seeking an explanation for his struggles.

Considering these findings, the neuropsychologist recommends a comprehensive measure of memory, to determine a more detailed profile of Jacob’s learning, and immediate, delayed, and recognition memory capabilities. They also suggest additional testing focused on measuring Jacob’s ability to engage in verbal and visual tasks of sustained attention, as weaknesses in honing attention can impact his ability to effectively store information in his short-term working memory.

*These data are completely fictional and are solely provided for illustrative purposes.

WJ V General Intellectual Ability (GIA)/Achievement Comparison Base-Rate Procedure: Janine & Reading

General Intellectual Ability (GIA)/Achievement

Notes. The predictor for each target cluster score is the examinee's earned standard score on the General Intellectual Ability (GIA) cluster. The difference score significance is based on ±1.50 SD (SEE).

Janine is a 9-year-old elementary school student who is being tested as part of an initial special educational evaluation. Her parents report concerns regarding her foundational literacy skills. As part of her initial evaluation, the school psychologist administers the General Intellectual Ability (GIA) cluster on the WJ V COG as well as the tests making up the Basic Reading Skills (Letter-Word Identification and Word Attack), Reading Fluency (Sentence Reading Fluency and Word Reading Fluency), and Reading Comprehension (Passage Comprehension and Paragraph Reading Comprehension) clusters which serve as the foundation for the analysis of Janine’s reading skills as compared to her predicted academic ability based on her Cognitive assessment.

Based on the above data, the school psychologist discovered that Janine demonstrates a significant weakness in the areas of Basic Reading Skills and Reading Comprehension. Her performance in these two areas are below what is predicted based on her cognitive ability (as measured by the WJ V COG) to a degree that is statistically significant.

Basic Reading Skills Interpretation: Janine’s ability to accurately decode real words and pseudowords tested lower than expected based on her cognitive ability. Her observed performance fell approximately 1.72 SDs below expected levels. The magnitude of difference between Janine’s actual and predicted Basic Reading Skills score is rare, only observed in 1% of those her same age.

Reading Comprehension Interpretation: Janine’s ability to demonstrate comprehension of written material also was lower than predicted by her cognitive scores. Her observed performance fell approximately 1.68 SDs below expected levels. The magnitude of difference between Janine’s actual and predicted Basic Reading Skills score is rare, only observed in 3% of those her same age.

Because of the clinical and statistical significance of Janine’s Basic Reading Skills and Reading Comprehension standard scores, when compared to her performance on the GIA cluster of the WJ V COG, the school psychologist recommends the IEP team consider eligibility for special education under the category of Specific Learning Disability. These standardized assessment scores are found to be congruent with other sources of data, such as curriculum-based measurement, teacher report, classroom observation, work samples, grades, and educational history, which leads the IEP team to move forward with eligibility with services in the areas of basic reading and reading comprehension.

*These data are completely fictional and are solely provided for illustrative purposes.