https://orcid.org/0009-0000-9106-9051
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ABSTRACT
Background
Ivanova and Hallowell Citation2013 emphasise the importance of reporting on test development and psychometric properties of tests in international journals. Such documentation may serve as references for other test developers and enable researchers and clinicians to assess reliability and validity issues in tests made for a language unknown to them.
The CAT (Comprehensive Aphasia Test) is a general aphasia test which examines linguistic skills broadly, within the cognitive neuropsychological tradition; it has been and is being adapted to a number of languages.
Aims
The aim of this article is to document the statistical procedures used in the development and standardisation of the Norwegian adaptation of the CAT (CAT-N), to document its psychometric properties, and to discuss validity and reliability issues.
Methods & procedures
The adaptation of the CAT-N involved careful design of subtests and test items, taking into account features like word frequency, imageability and phonological and other language-specific linguistic variables. The prototype was tested on a normative sample of 85 persons with aphasia and a control group of 84 persons without aphasia. The items of some subtests were reordered based on the norming. A new scoring scheme was developed for two subtests of Picture description. The CAT-N includes the Aphasia Impact Questionnaire (AIQ), which is a new patient reported outcome measure developed for the CAT.
Outcomes & Results
Statistical methods are documented and discussed. Descriptive statistics for subtests and linguistic domains are presented. Internal consistency and partial inter-rater and intra-rater reliability aspects are investigated and documented. Construct validity is investigated and documented by factor analysis. Sensitivity and specificity are investigated through pairwise comparisons for subtests and domains and the use of normal-language cutoff values. Concurrent validity is investigated through comparisons with results from an existing aphasia test for Norwegian (NBAA).
Conclusions
The CAT-N is shown to have good reliability and validity, and it distinguishes well between persons with and without aphasia. The article provides explicit documentation of design decisions which may be useful in future adaptations of the CAT.
Geolocation information
Norway
Acknowledgements
The authors thank the Collaboration of Aphasia Trialists funded by COST and the Tavistock Trust for Aphasia for their support in setting research priorities and promoting international/multidisciplinary collaboration in aphasia research. We furthermore thank the other members of the Norwegian adaptation team, Nina Høeg and Ingvild Røste.
Disclosure statement
This work was partly supported by the Research Council of Norway through its Centres of Excellence funding scheme [223265] and by Statped.
The authors report no conflict of interest.
Notes
1 Even though uncorrelated underlying factors could not be expected in this case, the orthogonal varimax rotation was chosen in order to accommodate comparison with the English version of the CAT (Swinburn et al., 2004) and simplify interpretation of the model (e.g. Stevens, 2009. p. 331).
2 The Word fluency subtest is included among the cognitive subtests, but contributes to the calculations of the linguistic domains.
3 We use the term domain where Swinburn et al. (2004) use modality in order to avoid confusion with what is commonly known as the fundamental linguistic modalities (listening, speaking, reading, writing).
4 In R, T-scores may be calculated according to this algorithm using the following command:
qnorm((rank(x, na.last=“keep”)-0.5)/length(na.omit(x)), m=50, sd=10)
where x is a vector variable holding all raw scores for a subtest or domain, i.e. the 85 PWA scores in this case. In SPSS, there is a ready-made menu option for Rankit transformation.