The design of Differential Ability Scales–Second Edition (DAS-II) comes out of a vision to provide the psychologist with insight into how a child processes information to devise appropriate interventions and/or recommendations for the classroom and at home.
The DAS–II is a comprehensive, individually administered, clinical instrument for assessing the cognitive abilities that are important to learning. The test may be administered to children ages 2 years 6 months (2:6) through 17 years 11 months (17:11) across a broad range of developmental levels.
The diagnostic subtests measure a variety of cognitive abilities including verbal and visual working memory, immediate and delayed recall, visual recognition and matching, processing and naming speed, phonological processing, and understanding of basic number concepts. Some of these subtests can be used with children ages 2:6–17:11, while others have specific age ranges.
“DAS-II helps you find out why a child isn’t learning, and targets the specific nature of the problem, so that appropriate intervention strategies can be identified. It’s a well-rounded assessment of a child’s strengths and ability that also enables measuring change over time, in order to monitor progress.”
Dr. Colin Elliott, DAS-II author
Features & Benefits
The Differential Ability Scales ® –Second Edition (DAS–II) continues the tradition of providing an in-depth analysis of children’s learning abilities. Using profile analysis, you can identify the child’s strengths and weaknesses so the appropriate IEP goals, intervention strategies, and progress monitoring can be developed. The DAS-II is appropriate for diverse populations as it can predict achievement on the basis of ability equally well for African American, Asian, Hispanic, and White/Non-Hispanic children. More information about the cultural fairness of DAS-II is available in the Technical Manual.
The DAS-II covers all ability levels for ages 2:6 – 17:11 split into two battery levels. For ages 5:0 – 8:11, both levels of the battery are fully co-normed, allowing the examiner to use subtests from either level of the battery, depending upon the child’s performance on the age-appropriate subtest. Additionally, the examiner can compare performance on the subtests tapping similar constructs from each battery to test hypotheses about the reasons for high or low scores. With DAS-II’s age range of 2:6-17:11 years, you can complete comparisons of test performance across time – even when normative scores cannot be obtained for a child of a given age, ability scores can be compared across time.
DAS-II is Theoretically Driven
- All major CHC broad abilities are represented in the DAS-II subtests and composites.
- Subtests map onto neuropsychological constructs, and reflect recent research in working memory and reading acquisition. Each subtest measures a homogeneous, reliable, and distinct set of cognitive abilities allowing clinicians the flexibility to use the test piecemeal with confidence.
- DAS-II uses state-of–the-art psychometric techniques that make the instrument time-efficient, yet produce the highest reliable subtest specificity of any cognitive battery. The result is effective profile analysis of an individual’s strengths and weaknesses in cognitive processing.
- Rasch modeling was applied to the construction of item sets to ensure ability levels were appropriate within each battery, resulting in only having to administer the items necessary to achieve a sufficient work sample, on a reliable subset of items. This efficiency helps children from experiencing boredom or fatigue by items that are either too easy or hard to reliably discriminate among age mates.
DAS-II is Child-Friendly
- Increased floor for all subtests allows all children to find success on at least a few items, providing clinicians an understanding of what a child can do while preserving the rapport with the child.
- Contains an abundance of teaching items to ensure a child does not fail because the instructions were not understood clearly.
- Presents a wide range of engaging, child-appropriate activities to elicit optimal performance and create a positive view of testing in general.
- Offers administration flexibility through out of level testing options with extended General Conceptual Ability (GCA) and cluster scores available for children experiencing cognitive delays.
- Offers Spanish translation and American Sign Language translation of the nonverbal subtest administration instructions.
- Tailored testing procedures reduce overall administration time, make maximum use of the child’s energy, and facilitate rapport.
Back to Top
What’s New with DAS-II
The original DAS has provided the strong cognitive foundations for the DAS-II. The revision has gone even further in translating cognitive development and cognitive process research findings into easily administered and interpreted subtests. The 20 cognitive subtests of the DAS-II include 17 subtests from the original DAS. The subtests are divided into two batteries based on age and are further subdivided into core and diagnostic subtests. Here are some of the new features:
- Updated normative sample representative of the general U.S. population
- New items and four new subtests—Recall of Sequential Order, Rapid Naming, Phonological Processing and Recall of Digits–Backward
- Block Building subtest is combined with the Pattern Construction subtest
- Matrices subtest now contains a set of items for young children
- Expanded clinical samples of children with a variety of special classifications (i.e., developmental risk; reading, writing, and math learning disabilities; attention-deficit/hyperactivity disorders; specific language impairment; limited English proficiency; mild to moderate intellectual disability; and gifted and talented)
- More engaging and contemporary artwork
- Modified the administration and scoring procedures to enhance the user-friendliness of the scale
- Spanish language translation of the nonverbal subtests
- CD with examiner instructions to assist with administration of the phonological processing subtest, and signed nonverbal subtest administration directions (signed sentences)
- Linked to WIAT-III to tap into all areas of disability, as specified in IDEA 2004
Back to Top
The diverse nature and individual reliability of the core and diagnostic subtests make the DAS–II a useful tool for profiling a child’s strengths and weaknesses. All 20 subtests involve activities that are appropriate to the developmental level of every child. The subtests are grouped into the Early Years and School-Age cognitive batteries with subtests that are common to both batteries and those that are unique to each battery. These batteries provide the General Conceptual Ability score (GCA), which is a composite score focusing on reasoning and conceptual abilities.
Early Years Cognitive Battery
The Early Years core battery includes verbal, nonverbal, and spatial reasoning subtests appropriate for ages 2:6 through 6:11. The battery is divided into two levels: children ages 2:6–3:5 and 3:6–6:11. The younger children are administered four core subtests to obtain the GCA composite score and children ages 3:6–6:11 take six core subtests which contribute to the GCA composite score. Although these subtests focus on ages 2:6-6:11, it can also be used to assess children ages 7:0–8:11 who are suspected of having cognitive delay.
There are eleven optional diagnostic subtests for this age group. There are also three optional diagnostic clusters: Working Memory, Processing Speed, and School Readiness.
School-Age Cognitive Battery
The School-Age core battery contains subtests that can reliably be used to assess children ages 7:0 through 17:11. These subtests measure verbal, nonverbal reasoning, and spatial reasoning abilities. The subtests can also be used to assess children ages 5:0–6:11 who may be cognitively gifted. In addition there are up to nine diagnostic subtests for this age group that feed into three possible diagnostic cluster scores: working memory, processing speed and, for the youngest ages, school readiness.
Back to Top
Out of Level Testing for those children at the extremes of ability ranges
As the clinician there are times when you might not know exactly who you are going to be testing on a given day, in a given school. The DAS-II offers you flexibility in being able to tailor the test based on the empirical observations you make about the child—from children with very low ability to children with giftedness. You can feel confident in your decision even when the test is tallied as the child will still be compared to a reference group of age mates – because all of these subtests were normed for his or her age mates.
The Early Years and School-Age batteries were normed for overlapping age ranges, and both were standardized with children ages 5:0–8:11. This overlap permits out-of-level testing and insures that bright, younger children and less able older children can be given subtests appropriate for their abilities. Gifted children have the opportunity to show just how much they can do, by taking subtests typically administered to older children. Children of very low ability also have the opportunity to demonstrate what they can do, through administering the appropriate DAS-II subtests.
In analyzing the normative information, two decisions were made to simplify the normative data tables. For all remaining ages outside the age range of 5:0-8:11 years, all subtests have sufficient floors and ceilings, except where explicitly indicated (by shading in the norms manuals). When a subtest is not reliable for a particular age, it is because the ability being measured is developmentally inappropriate for almost all children of that age. The subtest and cluster/composite standard scales were extending to four standard deviations on either side of the mean for each age band. This means the GCA goes down to 30, up to 170; and subtests go from T=10 to T=90.
There may be instances were you have a child of age 9 years or older who is unable to provide a sufficient work sample for the School Age battery. The DAS-II offers extended GCA, SNC and all cluster scores via backchannel. These extended norms will not provide much of a downward extension in terms of standard scores (only down to 25 as opposed to 30); however, they will allow a child of this ability to be tested using subtests on which they will find some success, and still be compared against the projected performance of their actual age-mates.
Offering this combination of scores makes the DAS–II useful for classifications and placement decisions that require an index of intellectual ability, for diagnostic testing that may contribute to understanding a child’s weaknesses and strengths, and for designing tailored interventions.
Back to Top
Clinical and Validity Studies
- Developmental Risk
- Intellectual Disability, including children with Down Syndrome
- Learning Disorder in Reading
- Learning Disorder in Reading and Writing
- Learning Disorder in Math
- Expressive Language Disorder
- Mixed Receptive/Expressive Language Disorder
- ADHD and a combination of Learning Disabilities (Reading , Writing, Math)
- Limited English Proficiency
- Deaf and Hard of Hearing
Validity Studies—Establishing Lines of Validity Evidence Cognitive Ability
- Bayley Scales of Infant Development–Second Edition
- KTEA-II – Kaufman Test of Educational Achievement Second Edition
- Woodcock Johnson- III
- Bracken School Readiness
- Ready to Learn
Back to Top
Areas of Assessment
The DAS-II still recognizes and defers to the judgment of the expert clinician, and provides the psychometric basis for allowing this kind of flexibility. The psychologist is encouraged to use his or her information about the child in the room to select a battery, subtests, and item sets that are appropriate to the ability of that child.
DAS-II Subtests Chart (PDF – 30kb)
- Special Population Application
- Determination of Learning Disabilities
- Determination of Intellectual Disability
- Testing Children who are not proficient in spoken English
- Testing Children who are hard of hearing
- Identifying Children for Giftedness
- Other Applications
- DAS-II as Part of a Neuropsychological Evaluation
- Using DAS-II for Research Purposes
Special Population Application
The DAS–II can be used as a psychoeducational tool to obtain an assessment of cognitive abilities. It is also useful as part of a comprehensive educational or neuropsychological assessment to identify cognitive strengths and weaknesses, intellectual giftedness, or intellectual disability. Results are intended to inform treatment planning and placement decisions in clinical and educational settings, and can provide useful clinical information for neuropsychological evaluation and research purposes.
With the DAS-II you can identify learning disabilities and intellectual disability and properly evaluate Spanish-speaking or deaf or hard of hearing children or giftedness.
Determination of Learning Disabilities
Tests of cognitive ability are used extensively in school settings to evaluate the specific cognitive deficits that may contribute to low academic achievement and to predict future academic achievement. To facilitate the assessment of learning disabilities, the DAS–II was linked with WIAT–III to provide information on both cognitive abilities and academic achievement in children from ages 6:0-17:11. Used in conjunction, the DAS-II and WIAT–III provide valuable information for both eligibility and educational intervention purposes.
With the new Phonological Processing Rapid Naming subtests, the DAS-II provides diagnostic subtests that measure cognitive abilities implicated in the dual-deficit hypothesis of developmental dyslexia. This is one of the differences that make a difference, in terms of differential treatment response (e.g., you don’t intervene with phonics when speed of lexical access is the sole deficit).
The DAS–II diagnostic subtests can be used in combination with other instruments specialized for the assessment of cognitive deficits underlying particular learning problems. For instance, poor performance on the Phonological Processing and Rapid Naming subtests may signal problems with the development of fundamental reading skills. In such cases, the Early Reading Success Indicator (ERSI) or the Process Assessment of the Learner: Test Battery for Reading and Writing (PAL) may be used with the DAS–II to enhance the clinical utility of each measure.
Pairing the DAS–II with the ERSI or the PAL provides corroborative information on processes and skills predictive of early reading ability, difficulties, or failure, while parsing out effects from other developmental conditions (e.g., attention-deficit/hyperactivity disorder or a central auditory processing disorder). Additionally, the PAL provides means of tracking a child’s progress in early intervention and prevention programs. Using DAS–II results in conjunction with the ERSI or PAL allows the examiner to go beyond the traditional use of ability-achievement discrepancies to determine eligibility for services, and helps school districts to more effectively respond to IDEA 2004.
The DAS-II includes measures of working memory and processing speed, two types of deficits that can underlie diminished performance across academic domains. This is another one of the differences that make a difference, in terms of differential treatment response (e.g., WM deficits are treated with WM interventions – teach encoding strategies, instead of drilling academic content for improvements across academic domains).
Back to Content List
Determination of Intellectual Disability
The DSM-5 and American Association on Intellectual Disabilities have defined diagnosing intellectual disability as significantly low performance on general cognitive ability with limited adaptive behavior ability.
The design structure of the DAS–II facilitates the assessment of children of very low ability. However, the most accurate diagnosis derives from multiple data sources, including assessment of the individual’s functioning at home, at school, and in the community. The Adaptive Behavior Assessment System–Second Edition (ABAS–II) may be used with the DAS–II to enhance the clinical utility of both measures. This pairing provides information on cognitive and adaptive functioning, both of which are required for the proper diagnosis of intellectual disability. In addition, assessment of cognitive functioning provides useful information for placement and training decisions.
Back to Content List
Testing Children who are not proficient in spoken English
Not only was DAS-II standardized using Spanish directions for the administration of the nonverbal subtests—Copying, Matching Letter-Like Forms, Matrices, Pattern Construction, Picture Similarities, Recall of Designs, Recognition of Pictures, Sequential and Quantitative Reasoning, and Speed of Information Processing, it also
- Offers an expert Spanish translation of nonverbal subtest directions (i.e., blind back translation, expert panel review)
- Provides the SNC, which is useful for testing all children who are not proficient in spoken English
- Gives you the means for a number of other subtractive methods that allow for specific hypothesis testing (e.g., Is limited English proficiency diminishing Word Definitions Scores for this 7-year-old?) Administer Naming Vocabulary, which has a reduced expressive language component, but still taps word knowledge
Best practice suggests that clinicians be well versed in the professional practice issues and ethical considerations of assessing children whose primary language is other than English. Spanish speakers may share a primary language with dialectical variations. However, these children will likely be diverse in many other respects. Examiners should familiarize themselves with the specific cultural and linguistic conditions of each child’s background when administering the DAS–II Spanish subtests and interpreting performance.
Back to Content List
Testing Children who are hard of hearing
The DAS–II provides the option to evaluate a client with a hearing impairment. Signed standard administration directions are Included on a CD for Copying, Matching Letter-Like Forms, Matrices, Pattern Construction, Picture Similarities, Recall of Designs, Recognition of Pictures, Sequential and Quantitative Reasoning, and Speed of Information Processing.
A child may use one or any combination of aural/oral or visual modes when communicating. Therefore, the communication method used to administer the DAS–II to a given child may differ across different languages and modalities (e.g., between manually signed American Sign Language and spoken English) with gradations, combinations, and systems in between. Items on the DAS–II may be conveyed differently depending upon the signs and sign language(s) used. The DAS-II provides general guidelines and caveats for administration of DAS–II subtests to children who are Deaf or hard of hearing.
Back to Content List
Identifying Children for Giftedness
Children ages 5:0-6:11 years can be administered the school-age battery. The DAS-II has better ceilings and the normative score range is wider than the previous edition. Subtest scores now run from 10 to 90 (that is, the mean plus and minus 4 SDs) and composite scores now run from 30 to 170 (that is, the mean plus and minus 4.67 SDs). A Gifted sample is also included in the validity studies.
It is appropriate to use the Special Nonverbal Composite (SNC) for identifying giftedness in children in non-White populations when the verbal scores are lower due to cultural or environmental influences. The DAS-II GCA score is unbiased in predicting achievement scores of African-American and Hispanic children and in some instances, over-predicts their achievement scores.
Back to Content List
DAS-II as Part of a Neuropsychological Evaluation
Children referred for assessment in clinical and educational settings frequently show indications of complex problems requiring thorough assessment of cognitive, functional, and neuropsychological functioning. These evaluations identify individuals who may have underlying neurobehavioral problems or are employed to provide an in-depth examination of the neurocognitive abilities of children with known neurological insults.
Neuropsychological evaluations are also used for differential diagnosis of neurological and psychiatric disorders. The psychometric properties of the DAS–II subtests allow for each to be interpreted in isolation, making all DAS–II subtests suitable for inclusion in customized, construct-based assessment batteries.
To incorporate information on memory functioning, the DAS–II can be used with the Children’s Memory Scale (CMS) or the NEPSY, both of which include a comprehensive measure of learning and memory functioning in children. These pairings enhance the clinical utility of the DAS–II by providing comprehensive information on children’s memory function, among other neuropsychological processes and also provides additional means of assessing the neuropsychological status of children with congenital or acquired brain dysfunction, damage, or disease.
Back to Content List
Using DAS-II for Research Purposes
The comprehensive age range of the DAS–II makes it especially useful in longitudinal studies because the need to switch instruments as the children age is significantly reduced. The psychometric properties of the DAS have been maintained in the DAS–II; in some areas the technical characteristics have exceeded that of DAS, allowing for continued confidence in the DAS–II as a viable research instrument.
The DAS–II can be used to examine the performance of children in a particular diagnostic group or to track the effects of intervention on children’s cognitive development. For example, researchers can use the DAS–II to determine the effects of traumatic brain injury on cognitive functioning or to examine whether the effectiveness of school-based interventions varies with specific cognitive abilities. The latter use has special implications for research into the changes in cognitive mechanisms that predict differential response to interventions.
Back to Content List