Vineland Adaptive Behavior Scales-II:
Issues Related to Result Interpretation and Test Validity
Vineland Adaptive Behavior Scales-II:
Issues Related to Result Interpretation and Test Validity
The Vineland Adaptive Behavior Scales-II (Vineland-II; Sparrow, Cicchetti & Balla, 2004) is a psychometric test used to measure adaptive behavior. Adaptive behavior is defined as the ability to achieve a level of personal independence and social responsibility consistent with expected levels from individuals cultural and age group (Perry & Factor, 1989). The Vineland-II test is comprised of four domains of adaptive behavior: (1) Communication, (2) Daily Living, (3) Socialization, and (4) Motor Skills. The Maladaptive Behavior Index measures maladaptive behaviors, which are defined as behaviors that interfere with daily activities (e.g. obsessive behaviors, destructive behaviors, self-injury, impulsivity, being temperamental, inappropriate sexual behaviors, etc.), and it is an optional domain that can be used when necessary.
The extent of adaptive behavior development is dependent on age, so the levels of adaptive behavior need to be considered within the developmental context. However, the ability to develop adaptive behaviors is also dependent on mental health, so individuals with intellectual disability or developmental disorders will display adaptive behavior deficits. A routine assessment of adaptive behavior levels in individuals with intellectual disabilities or developmental disorders associated with adaptive behavior deficits and maladaptive behaviors is recommended for educational and therapeutic purposes (Perry & Factor, 1989).
According to Sparrow et al. (2004), a nationally representative sample of 3,695 participants from the US, age range from birth to 90 years, was used to test the reliability and validity of Vineland-II. The results showed average to excellent internal consistency and test-retest reliability across all age groups. The base rate for the test is the score of 100, which is calculated based on the mean score for a specific population, with a standard deviation of 15. The clinical population had a significantly lower mean score than the non-clinical population at 2 standard deviations below the base rate.
Despite the good reliability and validity of the Vineland-II test, it is important to note that hit rates, miss rates, false positive errors, and false negative errors have to be considered when interpreting test results and evaluating the instrument’s validity (Cohen, Swerdlik & Sturman, 2010). The hit rate defines the accuracy of the tests and is expressed as the percentage of people who are correctly identified with a certain behavior or characteristic. The miss rate defines the percentage of people whose behaviors or characteristics are incorrectly identified as lacking or present. Therefore, miss rates can be categorized as false positives or false negatives. A false positive error refers to the prediction that the test-taker possesses a behavior or characteristic when that behavior or characteristic is actually lacking. A false negative error refers to the prediction that the test-taker does not possess a behavior or characteristic when that behavior or characteristic is actually present.
Although adaptive behavior deficits are predictive of intellectual disabilities and other developmental disorders, a low hit rate is possible when the Vineland-II test is used as a diagnostic tool. The original evaluation of the Vineland-II test by Sparrow et al. (2004) reported that clinical populations had significantly lower mean scores than the general population, but the clinical population consisted of a diverse sample and included participants with a variety of disorders, which included cognitive delayed development, autism, attention-deficit/hyperactivity disorder, learning disability, visual impairment, hearing impairment, and emotional or behavioral disturbance. Each clinical group has a distinctive profile based on the types of adaptive behavior deficits they experience. For example, individuals with autism spectrum disorder (ASD) have good scores in the Daily Living and Motor Development domains, but they have a low Adaptive Behavior Composite score, a low score in the Socialization domain, and a distinctively low score in the Communication domain (Robins, 2008; Lee et al., 2010). Individuals with other disorders will not always display consistent adaptive behavior deficits, so using the Vineland-II for diagnostic purposes in certain population could result in a low hit rate.
For example, the test is not applicable in all cases of intellectual disability because the test measures only four broad domains of adaptive functioning (Pennington, 2009). If a child with intellectual disability shows an adaptive functioning deficit in only one domain, that evidence will not be sufficient to support an intellectual disability diagnosis. On the other hand, a comprehensive clinical interview that addresses 11 areas of adaptive functioning could result in a diagnosis of intellectual disability even when the Vineland-II fails to measure the presence of adaptive functioning deficits in one of the four domains measured (Pennington, 2009). Therefore, screening adaptive behavior deficits with Vineland-II provides good guidelines for clinicians to evaluate the patient’s adaptive functionality in different domains and plan interventions accordingly, but it should only be used as a supplemental tool in the diagnostic process to avoid low hit rates.
Although Vineland-II is currently considered as one of the reference standard tests for identifying the adaptive behavior deficits associated with ASD (Lee et al., 2010), which indicates that it has a good hit rate for that population, the accuracy of the test’s cut-off scores has been criticized (Wehmeyer, 2013). The initial evaluation of the test by Sparrow et al. (2004) indicated that the mean Vineland-II scores for clinical populations were 70 (i.e. 2 standard deviations below the standard scores), but the age range of the participants was from birth to 90 years of age, and it is important to consider that the adaptive behavior mean scores are negatively associated with aging. Children also have lower mean scores because development is positively associated with adaptive functioning. Consequently, standard deviations will vary across age groups, so each population will have a different cut-off score. That is why population-specific reference values need to be used in order to measure the degree of adaptive behavior accurately when working with individuals from different age groups and populations (Lee et al., 2010). However, the fact that standard scores change with age indicates that the test has high construct validity (Cohen et al., 2010), so it is highly likely that the test will have good hit rates for measuring the adaptive behavior construct as long as population-specific reference values are used to analyze results.
The large cut-off score used for interpreting the Vineland-II test results could lead to high miss rates. As a general rule, a larger cut-off score increases the chances of false positive miss rates while a smaller cut-off score increases the number of false negative miss rates (Cohen et al., 2010). The cut-off score of 70 is large compared to the standard score of 100 for the Vineland-II test. The large cut-off score increases the chances of false positive miss rates, which means that some people who may have adaptive behavior deficits will be categorized as people without deficits. That is why age-equivalent and population-specific scores and standard deviations need to be considered when interpreting the results of the Vineland-II test to avoid false-positive errors.
The high possibility of false positive miss rates could also be attributed to the fact that the Vineland-II test measures only four broad domains of adaptive behavior that are further divided into three subdomains. For example, the Socialization domain is divided into Interpersonal Relationships, Play and Leisure Time, and Coping Skills. An individual may have high scores in the Relationships and Play and Leisure Time subdomains, but a very low score in the Coping Skills subdomain. However, the overall score will most likely be above the cut-off for the Socialization domain, and it is possible to overlook the adaptive behavior deficit in the Coping Skills subdomain. Perhaps the test’s validity and accuracy could be improved by treating each subdomain as a separate domain rather than evaluating adaptive behaviors based on the broad domains Vineland-II uses to measure adaptive behavior.
False negative errors are less likely to occur than false positive errors when using the Vineland-II test because of its large cut-off score, but they can occur if the Vineland-II is the only test used for diagnostic purposes. Although the Vineland-II test is homogeneous because all of its domains measure the adaptive behavior construct, the current criteria for diagnosing intellectual disabilities require proof of both intellectual and adaptive functioning deficits (American Psychiatric Association [APA], 2013). If an individual is diagnosed with intellectual disability based on the evidence of adaptive functioning deficits without considering intellectual function deficits, the diagnosis could prove to be a false negative error. Otherwise, the homogeneity of the Vineland-II is high because all of its domains measure a single construct and are consistent with adaptive functioning domains used by APA (2013) as diagnostic criteria for intellectual disabilities, so the high construct validity contributes to the low prevalence of false negative errors.
Vineland-II is a reliable and valid tool for assessing adaptive behaviors, but the accuracy of its cut-off scores has been criticized. It is not recommended to rely on the tool for diagnostic purposes because it assesses only four broad dimensions of adaptive behaviors, which can lead to low hit rates because it does not provide sufficient evidence regarding the presence of intellectual disabilities or developmental disorders. The lack of homogeneity among individuals with different types of intellectual or developmental disorders is also a potential cause of low hit rates as they will show deficits in different domains of adaptive behavior, but the test is considered reliable for diagnosing ASD and is one of the reference standards for assessing that population. False positive miss rates are likely to occur because of the large cut-off score used, but false negative miss rates will occur less likely because the test has high internal consistency.
References
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders. (5th ed.). Arlington, VA: American Psychiatric Publishing
Cohen, R. J. Swerdlik, M. E., & Sturman, E. D. (2010). Psychological testing and assessment: An introduction to tests and measurements. New York, NY: McGraw-Hill.
Lee, H., Marvin, A. R., Watson, T., Piggot, J., Law, J. K., Law, P. A., & Nelson, S. F. (2010). Accuracy of phenotyping of autistic children based on internet implemented parent report. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics, 153(6), 1119-1126.
Pennington, B. F. (2009). Diagnosing learning disorders: A neuropsychological framework. (2nd ed.). New York, NY: The Guilford Press.
Perry, A., & Factor, D. C. (1989). Psychometric validity and clinical usefulness of the Vineland Adaptive Behavior Scales and the AAMD Adaptive Behavior Scale for an autistic sample. Journal of Autism and Developmental Disorders, 19(1), 41-55.
Robins, D. L. (2008). Screening for autism spectrum disorders in primary care settings. Autism, 12(5), 537-556.
Sparrow, S. S., Cicchetti, D. V. & Balla, D. A. (2004). Vineland Adaptive Behavior Scales: Second Edition (Vineland-II). Bloomington, MN: Pearson Assessment.
Wehmeyer, M. L. (2013). The Oxford handbook of positive psychology and disability. New York, NY: Oxford University Press.
