American Disability Test Norms May Not Fit German-Speaking Children, Study Warns

A widely used pediatric assessment that measures how independently children manage everyday life may not translate as seamlessly across cultures as clinicians have assumed. A new exploratory study published in the Scandinavian Journal of Occupational Therapy examined whether the American normative scores of the Paediatric Evaluation of Disability Inventory – Computer Adaptive Test, known as the PEDI-CAT, can be applied to German-speaking children in Switzerland and Germany. The answer, according to researchers Christina Schulze of the Zurich University of Applied Sciences, Myrthe Mali of Eastern Switzerland Children’s Hospital, and Anders Kottorp of Malmö University, is a cautious no – at least not yet, and not without further evidence.

The PEDI-CAT is a computer adaptive clinical assessment designed for children and young people from birth through twenty years of age, covering a wide range of physical and behavioral conditions. It grew out of the original Paediatric Evaluation of Disability Inventory, first published in 1992, and expanded it substantially. Where the original instrument measured three functional domains, the PEDI-CAT adds a fourth. The Daily Activities domain contains 68 items, Mobility contains 97, Social/Cognitive Function contains 60, and the Responsibility domain, which measures how far the child or caregiver takes charge of complex, multi-step life tasks, contains 51 items drawn from a total bank of 276 functional activities acquired across infancy, childhood, and young adulthood.

What makes the instrument distinctive is its adaptive engine. Parents, caregivers, or professionals familiar with the child rate each item as unable, hard, a little hard, or easy, with an additional option of I don’t know that prompts the software to substitute another item of equivalent difficulty. When a respondent marks an item as easy, the algorithm selects a harder item next. In this way, the test homes in on the child’s actual functional level, administering fewer irrelevant questions, shortening the assessment, and increasing precision at the same time. The Responsibility domain uses its own five-point scale, ranging from full adult or caregiver responsibility to the child taking complete responsibility without any directions.

The theoretical backdrop for the study is the International Classification of Functioning, Disability and Health for Children and Adolescents, which frames disability as a potential consequence of the interaction between a person’s characteristics and the environment in which that person lives. Modern pediatric rehabilitation therefore emphasizes functional performance and participation in daily activities rather than body structures alone, and standardized assessments of activities of daily living are central tools for evaluating functioning, setting treatment goals, and measuring change. But daily activities are deeply shaped by context: physical settings, social support, cultural norms, and available resources all influence how children engage in dressing, eating, mobility, and social tasks.

That contextual sensitivity is precisely why the researchers questioned whether norms derived from an American sample could be exported to the German-speaking world. Germany, Austria, and Switzerland differ from the United States in cultural values, educational systems, and socioeconomic factors, and earlier cross-cultural studies of the original PEDI in countries from Norway and Sweden to Taiwan, Turkey, Puerto Rico, and Saudi Arabia repeatedly concluded that normative scores should be developed or adapted for each country’s specific cultural and societal context. Even European studies that found only minor differences from the American norms generally recommended country-specific investigation. The Netherlands, notably, had already tested the PEDI-CAT’s American norms against Dutch children and found no significant differences – but no equivalent check had ever been performed for the German version of the test, published in 2020.

The team adopted an exploratory cross-sectional design, recruiting 112 children aged four to eight years through convenience sampling via social media, schools, hospitals, and private occupational therapy practices between January and April 2022. Inclusion criteria required that the children attend mainstream school in Switzerland or Germany, be free of any known disability, and receive no therapeutic treatment, and that their parents communicate sufficiently in German and sign informed consent. The final sample comprised 51 Swiss and 61 German children with a mean age of 5.78 years, a standard deviation of 1.39 years, and a range of 4.10 years. The age window was chosen deliberately, since the years between four and eight are crucial for the development of basic activities of daily living. Ethical approval was obtained from the relevant committees in both countries, and the German version of the PEDI-CAT was administered through the online Q-global platform operated by the test’s publisher, Pearson.

The statistical strategy proceeded in two stages. First, the researchers compared the Swiss and German samples using independent two-samples t-tests, supported by Shapiro-Wilk tests confirming normal distribution in both groups. No significant differences emerged across any PEDI-CAT domain, and effect sizes were negligible, with the German children scoring only minimally higher. The two samples were therefore merged into a single German-speaking sample. In the second stage, the team used one-sample t-tests to compare that merged sample against the American normative standard scores, which are expressed as T-scores with a mean of 50 and a standard deviation of 10, meaning that roughly 95 percent of a typical population should fall between 30 and 70. Effect sizes were evaluated with Cohen’s d criteria.

The results were striking. Statistically significant differences with medium to large effect sizes appeared in all four domains. In Daily Activities, the German-speaking children scored significantly higher than the American norm, with a large effect (t(111) = 9.25, p < .001, d = 0.87). Mobility showed a moderate effect (t(111) = 7.43, p < .001, d = 0.7), Responsibility a moderate effect (t(111) = 6.74, p < .001, d = 0.64), while Social/Cognitive Function went the other way, with the German-speaking children scoring significantly lower than the American norm (t(111) = −7.51, p < .001, d = −0.71). Yet the picture was not one of wholesale incompatibility: 95 percent or more of all individual scores fell within the two-standard-deviation norm range of 30 to 70. Every one of the 112 scores landed inside that range for Daily Activities and Social/Cognitive Function, 107 of 112 (95.5 percent) for Mobility, and 111 of 112 (99.1 percent) for Responsibility. The six children who fell outside the range all scored above 70, meaning they outperformed rather than underperformed the American expectations.

The researchers offer several interpretations. The lower Social/Cognitive scores mirror a pattern found in the Dutch validation study, suggesting that translated items or rating-scale categories may be interpreted somewhat differently across contexts. The findings also sit in tension with earlier work by Wenger and colleagues, who concluded that the American norms of the original PEDI were equivalent for German-speaking populations in Switzerland, Austria, and Germany. One provocative hypothesis is that the PEDI-CAT’s expanded and reworked item set is simply more sensitive to the contextual and environmental factors that shape children’s everyday functioning – a property that would make cross-cultural differences more visible, not less real. The authors caution, however, that with small numbers of children in individual age groups, they cannot conclusively determine whether the observed differences arose systematically or by chance, and the lack of demographic detail, including the proportion of immigrant families in the samples, limits interpretation of cultural background effects.

Methodological limitations temper the conclusions further. The non-randomized convenience sampling strategy may bias representation of the general population, some individual age groups were too small for generalizable conclusions, and the study covered only a slice of the PEDI-CAT’s full birth-to-twenty age range. Nothing is known about how parents’ education, age, native cultural background, or beliefs about daily activities influenced their response patterns. Still, the practical message for clinicians is clear: the American normative standard scores should be applied to the German version of the PEDI-CAT with caution for now. The authors recommend larger, randomized, and representative samples spanning the full age range to confirm or refute these preliminary findings – a reminder that even the most sophisticated adaptive testing technology cannot escape the cultural soil in which childhood independence takes root.

Subject of Research: Cross-cultural validation of American normative scores for the German PEDI-CAT pediatric functional assessment

Article Title: Cross-cultural validation of the German Paediatric Evaluation Disability Inventory – Computer Adaptive Test: A comparative study with American normative standard scores

Article References: Schulze, C., Mali, M., & Kottorp, A. (2025). Cross-cultural validation of the German Paediatric Evaluation Disability Inventory – Computer Adaptive Test: A comparative study with American normative standard scores. Scandinavian Journal of Occupational Therapy, 32(1), Article 2505417. https://doi.org/10.1080/11038128.2025.2505417

Image Credits: AI Generated

DOI: 10.1080/11038128.2025.2505417

Keywords: PEDI-CAT, pediatric assessment, cross-cultural validation, activities of daily living, normative scores, psychometrics, child development, disability inventory, occupational therapy, Germany, Switzerland, computer adaptive testing