Validation of the Chinese Handwriting Analysis System (CHAS) for primary school students in Hong Kong.

There are more children diagnosed with specific learning difficulties in recent years as people are more aware of these conditions. Diagnostic tool has been validated to screen out this condition from the population (SpLD test for Hong Kong children). However, for specific assessment on handwriting problem, there seems a lack of standardized and objective evaluation tool to look into the problems. The objective of this study was to validate the Chinese Handwriting Analysis System (CHAS), which is designed to measure both the process and production of handwriting. The construct validity, convergent validity, internal consistency and test-retest reliability of CHAS was analyzed using the data from 734 grade 1-6 students from 6 primary schools in Hong Kong. Principal Component Analysis revealed that measurements of CHAS loaded into 4 components which accounted for 77.73% of the variance. The correlation between the handwriting accuracy obtained from HAS and eyeballing was r=.73. Cronbach's alpha of all measurement items was .65. Except SD of writing time per character, all the measurement items regarding handwriting speed, handwriting accuracy and pen pressure showed good to excellent test-retest reliability (r=.72-.96), while measurement on the numbers of characters which exceeded grid showed moderate reliability (r=.48). Although there are still ergonomic, biomechanical or unspecified aspects which may not be determined by the system, the CHAS can definitely assist therapists in identifying primary school students with handwriting problems and implement interventions accordingly.