Differential Ability Scales-II

The DAS–II is an individually administered, clinical instrument for assessing the cognitive abilities that are important to learning. Use DAS-II to identify learning disabilities and intellectual disability and properly evaluate Spanish-speaking or deaf or hard of hearing children or giftedness.

Benefits

• Identify a child’s strengths and weaknesses so the appropriate IEP goals, intervention strategies, and progress monitoring can be developed.
• Predict achievement on the basis of ability equally well for African American, Asian, Hispanic, and White/Non-Hispanic children.
• Compare performance on the subtests, tapping similar constructs from each battery to test hypotheses about the reasons for high or low scores. 
• Compare ability scores over time, even when normative scores cannot be obtained for a child of a given age.
• Can be used with Children’s Memory Scale or NEPSY to incorporate information on memory function.

Features

The DAS–II is built upon the strong cognitive foundations of the original DAS. It has 20 cognitive subtests, including 17 subtests from the original DAS. Two of the original DAS subtests, Block Building and Pattern Construction, have been combined and four new subtests added.

The subtests are organized in two batteries based on age: Early Years and School-Age. The subtests in each battery are subdivided into core and diagnostic subtests. Additional new features include:

• Updated normative sample representative of the general U.S. population. The Early Years and School-Age batteries were normed for overlapping age ranges, and both were standardized with children ages 5:0–8:11.
• Four new subtests: Recall of Sequential Order, Rapid Naming, Phonological Processing and Recall of Digits–Backward.
• Subtests map onto neuropsychological constructs, and reflect recent research in working memory and reading acquisition. 
• Clinical samples expanded to include children with a variety of special classifications: 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.
• Modified administration and scoring procedures to enhance the user-friendliness.
• Spanish language translation of directions for nonverbal subtests.
• CD with examiner instructions to assist with administration of the phonological processing subtest, and signed nonverbal subtest administration directions (signed sentences).

Clinical 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
• ADHD
• Limited English Proficiency
• Deaf and Hard of Hearing

Validity Studies

• Bayley Scales of Infant Development | Second Edition
• WISC-IV
• WPPSI-III
• WIAT-III
• KTEA-II 
• Woodcock Johnson- III
• Bracken School Readiness
• Ready to Learn

Sample Reports

The DAS–II provides five types of norm-referenced scores: ability scores,T scores, cluster scores, composite scores and percentile ranks.

DAS-II Sample Report

The following resources are available for DAS-II

Reference Materials

• Types of Scores Available for Subtests, Clusters and Composites
• Descriptions and Abbreviations of Abilities Measured
• Corrected Administration and Scoring Manual page 219
• Corrected Introductory and Technical Handbook page 237
• Technical Report--Ability-Achievement Discrepancy Table for use with the WIAT-II
• DAS-II Brochure
• DAS-II Update Letter

DAS-II Extended Norms Tables

• Extended General Conceptual Ability (GCA) Scores
• Extended Special Nonverbal Composite (SNC) Scores
• Extended Verbal, Nonverbal and Spatial Cluster Scores

Select a question below to see the response.

New Features

What’s New with DAS–II?

The DAS–II is built upon the strong cognitive foundations of the original DAS. The revision has gone even further, translating cognitive development and cognitive process research findings into easily administered and interpreted subtests. The DAS–II has 20 cognitive subtests, which includes 17 subtests from the original DAS. Two of the original DAS subtests, Block Building and Pattern Construction have been combined and four new subtests have been added. The subtests are organized in two batteries that are based on age. The subtests in each battery are subdivided into core and diagnostic subtests. Here are more of the new features:

• Updated normative sample representative of the general U.S. population
• Four new subtests—Recall of Sequential Order, Rapid Naming, Phonological Processing and Recall of Digits–Backward
• The Matrices subtest now contains a set of items for young children, ages 3:6–17:11
• The clinical samples were expanded to include children with a variety of special classifications: 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
• Spanish language translation of directions for the nonverbal subtests
• A CD with examiner instructions is included in the kit to assist with administration of the phonological processing subtest, and signed nonverbal subtest administration directions (signed sentences)

Why were the achievement subtests removed from the DAS–II?

The previous achievement portion was a screener, rather than a comprehensive achievement test. The WIAT–III link provides much richer data, allowing the clinician to predict and examine discrepancies for all WIAT–III composites. In addition to the GCA and Special Nonverbal Composite comparisons, there are now comparisons for the Verbal Cluster, and Nonverbal Reasoning Clusters and the Spatial Cluster. Also included are comparisons for each of the nine WIAT–III subtests.

Where is the small pencil that was once included in the Verbal Comprehension toy box?

The small pencil has been replaced by the large primary grip pencil included in your DAS-II kit. When administering Verbal Comprehension, place this pencil among the array of objects that you arrange for this portion of the subtest.

General

Why is DAS–II not an IQ test?

The DAS–II measures a more specific and narrower domain of human cognition. Although DAS–II provides a General Conceptual Ability composite, its primary purpose is as a tool for identifying and understanding the strengths and weaknesses in individuals. When describing an individual’s performance, it is recommended that you primarily focus on patterns of cognitive strengths and weaknesses, rather than the GCA score.

How can I make it easier for me to transport the DAS-II kit?

Pack only the components you'll need to administer the test in your new DAS--II rolling bag. Leave the Technical Manual and any protocols you won't need in your office.

Scoring and Interpretation

What type of test scores are provided with DAS-II?

The DAS–II provides five types of norm-referenced scores: ability scores, T scores, cluster scores, composite scores and percentile ranks. Confidence intervals are available for the cluster and composite scores. The composite score reflects conceptual and reasoning abilities, cluster scores measure more specific ability areas (verbal comprehension, nonverbal and spatial reasoning). Standard error of measurement information and age equivalents are provided for the subtest ability scores. Individual subtest scores represent a range of diverse abilities. For a quick overview of the types of scores available for subtests and composites, click here.

How does DAS–II guide me in determining if a client has a learning disability?

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–II to provide information on cognitive abilities and academic achievement in children from ages 6:0–17:11. Used together, the DAS–II and WIAT–II provide valuable information for both eligibility and educational intervention purposes.

The DAS–II diagnostic subtests can be used in combination with other instruments specialized for the assessment of cognitive deficits that underlie 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. Pairing the DAS–II with the ERSI or the PAL-II 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). The PAL-II also provides a means of tracking a child’s progress in early intervention and prevention programs. Using DAS–II results with the ERSI or PAL-II enables 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 the reauthorization of the Individuals with Disabilities Education Improvement Act of 2004 (IDEA).

Without a training CD, how can I complete the Copying and Recall of Designs scoring exercises?

Please consult Appendix B of the Administration and Scoring Manual for more detailed guidelines on scoring the drawing tasks. For practice, you can apply the scoring criteria to the sample drawings. The fact that the drawings have been photographically reduced does not affect pass/fail judgments.

Why should a child have different ability scores from two different item sets?

To answer this question, we will use a scoring example drawn from the Recall of Designs subtest. Here's a question posed by an examiner:

"A 6-year-old child gets 22 points in Item Set 1–12. You reach the decision point at Item 12, and because the child has apparently passed all but two items with maximum scores, you go on to the next decision point at Item 16. The child gets no more points. The child's ability score for a raw score of 22 on Item Set 1–12 is 106. The child's ability score for a raw score of 22 on Item Set 1–16 is 95. Why is it so different?"

The child, earning 22 out of a possible 24 raw-score points, has missed only 2 points on Item Set 1–12. The first thing to note is that the ability score of 106 falls within the shaded area on the Raw Score to Ability Score table. This indicates that having only two missed points does not give us sufficient information for us to make a reliable estimate of the child's ability. Note here that the standard error of measurement (SEM) is 8 (the SEM is the small number in parentheses next to the ability score). A larger SEM is another indication of a less reliable score. So we need to continue to administer additional items (13–16), as the examiner did, and then base the scoring on all responses from 1 to the next decision point, after Item 16.

On Items 13–16, the child scores 0 points. At Item 16, she therefore has a raw score of 22, with an ability score of 95 (SEM = 5) for Item Set 1–16. Note that this raw score and this ability score are in the white, unshaded area. Also, the SEM for this ability score is lower than that of the score we obtained that fell into the shaded area. Quite correctly, testing discontinues at this decision point.

The general rule for deciding which ability scores (and corresponding T scores) to use is this: When you have a choice of two or more ability scores from different item sets, use the one with the smallest SEM. In this case, the ability score with the smaller SEM is from Item Set 1–16 (Ability Score = 95, SEM = 5). The smaller SEM indicates that we have greater confidence in the accuracy and reliability of that ability score. It is that score that should be used as the basis for reporting the child's normative T score.

Here's another general rule to help you decide which ability score to use: If you have a choice of two item sets with identical SEMs for the two ability scores, use the one that included the most items. In our example above, the child actually could be scored for Item Set 4–16, on which she obtained a raw score of 16 (Ability Score = 94, SEM = 5). Even though the SEM is the same (i.e., 5) for the ability scores estimated from Item Sets 1–16 and 4–16, the ability score for Item Set 1–16 should be used because it covers more items.

Wherever possible, you should not stop testing if you find that converting a child's raw score to ability score falls into a shaded area on the Raw Score to Ability Score table. The shaded areas indicate very few passes (at the lower end) or very few failures (at the upper end) on the item set. They also indicate that an easier or more difficult item set is available and should be used. However, carefully following the administration rules for Decision Points will prevent a score from falling in the shaded area, except when it is unavoidable because the child cannot pass the first few items or passes the most difficult items on the subtest.

However, a key issue remains in the question: "WHY are the two ability estimates so different?" There are two possible influences at work here. First, it may just be due to random error of measurement. Measures of human abilities are never perfectly precise. We must remember that we are always making estimates. And the very few points missed in Item Set 1–12 of this example make us relatively uncertain about where the child's ability truly lies. In other words, Item Set 1–12 was too easy to provide an accurate measurement for this child, as shown by the shaded-area scores and relatively high SEMs.

The second influence at work may be something more systematic. Look again at the Raw Score to Ability Score table on the front of the School-Age Record Form. In our example, the child achieved a raw score of 22 on Item Set 1–12. With an ability score of 106 (all other things being equal) we would expect her to obtain a raw score of about 26 on Item Set 1–16; if you look at the second column of the table, you will see that this is the raw score corresponding to an ability score of 105. In other words, if a child was able to obtain an ability score of 106 for Item Set 1–12, we would have normally expected that child to obtain an extra 4 points on Items 13–16 so that the ability score would be close to, or the same as, that obtained by the earlier item set.

However, the child's inability to score any additional points after Item 12 may tell us something about the child and her approach to problem solving. Sudden and unexpected failure of this kind can often be observed in children who have had much experience with failure. They hit something challenging and cave in, saying they can't do it. That's one possible clinical hypothesis to explain this sort of sudden failure.

One might also observe behavioral indications supporting such an interpretation of sudden failure on relatively difficult items. For example, the child may show signs of visual avoidance of the problem (looking away after a very brief look at the item), or may respond impulsively on items that clearly require more thought and analysis. A frequent strategy used by some children is just to say, "I don't know" or "I can't remember" without attempting a response.

Most children respond roughly according to prediction; however, it is the students who do not respond in the classroom according to expectation who are typically referred for assessment. We need to be alert for unusual item response patterns!

To summarize our recommendations:

• Never be tempted to report a score based on an ability estimate that falls within the pale green or blue shaded bands in the Raw Score to Ability Score tables on the Record Form. Do this only if it was impossible to administer additional items.
• When you have a choice of two or more ability scores from different item sets, use the one with the smallest SEM.
• When you have a choice between two ability scores that have the same SEM, use the item set with the greatest number of items administered.

Specific Populations

May I use DAS–II to diagnose intellectual disability?

Although the design structure of the DAS–II facilitates the assessment of children of very low ability, 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 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. This pairing of the Adaptive Behavior Assessment System–Second Edition (ABAS–II) with the DAS–II 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.

Is the DAS–II appropriate to use with a child from a culturally and linguistically diverse background?

Although the design structure of the DAS–II facilitates the assessment of children of very low ability, 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 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. This pairing of the Adaptive Behavior Assessment System–Second Edition (ABAS–II) with the DAS–II 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.

May I administer the DAS–II to a child who has limited English proficiency?

If you are certain that the child has limited English proficiency, you may administer the nonverbal subtests and communicate the instructions in the child’s primary language or by gesture. Given that this is an accommodation and not a modification, you can still use the norm-referenced scores available for children who are proficient in English. The DAS–II also provides translations for standard administration directions to accommodate children who speak Spanish or use sign language, rather than spoken English, to communicate. As always, any departure from standardized administration procedures should be noted and described on the Record Form and considered when interpreting test results.

Is the DAS-II appropriate for children who are Deaf/Hard of Hearing?

Many DAS-II subtests are appropriate for testing children who are Deaf/Hard of Hearing, but several are not. Please consult your DAS–II Technical Handbook, chapter 9, for more information about the appropriateness of DAS–II subtests with this diverse population.

I am not fluent in ASL. Can I just play the Signed Standard Sentences CD for a Deaf/Hard of Hearing child, and record his or her answers?

No. In fact, the training CD presents the demonstration items out of sequence to illustrate changes in instructions. The CD is not meant for actual administration of the test.

Can a severely impaired child age 9:0 or older be tested with the Upper Early Years level of the battery?

Yes. When a child age 9:0 or older is unable to establish a sufficient work sample (at least 3 items correct) on more than one subtest from the School-Age battery, it may be appropriate to administer the Upper Early Years level of the battery. When you do so, you need to obtain the extended norms for children ages 9:0 and above from a customer service representative.

When administering a battery out of level, can I still make substitutions?

Yes. However, please remember that only one substitution is allowed from the alternative battery

Administration

I have a child whose age spans both batteries. Which battery should I administer?

The DAS–II Early Years and School-Age batteries were normed for overlapping age ranges, and both were standardized with children ages 5:0–8:11. Select the appropriate subtests based on your clinical judgment. For children who may have below-average cognitive ability, administer the Early Years battery because of the lower floor for this age range. For children of above-average ability, consider administering the School-Age battery because of the higher ceiling. The Early Years battery is appropriate for most children ages 6:0–6:11 of average ability. The School-Age battery is appropriate for most children ages 7:0–8:11. By definition, the majority of children are in the average ability range.

I have a child in the 7:0–8:11 age range with a language impairment. May I still administer the DAS–II?

Administering the verbal portion of the Early Years battery to older children with language impairments or verbal or expressive difficulties may reduce the confounding effects of language or the demand of complex verbal expression on composite scores. Please refer to the DAS–II Technical Manual for information on how to use the test and compare results with the results of studies with clinical groups with known language impairments.

Product Training

The DAS-II Administration and Scoring Manual mentions a training CD (p. 13). Is such a CD available for purchase?

No. The only training CD available is the one demonstrating an ASL administration of the nonverbal subtests. Contact your regional Clinical Consultant for training opportunities.