Development of the Handwriting Legibility Scale (HLS): A preliminary examination of Reliability and Validity

Background Demands for the production of legible handwriting produced in a timely manner increase as children progress through school. Despite the considerable number of children faced with handwriting difficulties, there is no quick and practical tool to assess legibility in this population. Aim The aim of this study was to develop the Handwriting Legibility Scale (HLS) and to establish the scale's reliability and validity. Methods The HLS is a non-language dependent scale which assesses global legibility, based on five criteria applied to samples of ‘free writing’. Content validity, inter-rater reliability and internal consistency were initially examined using scripts from 20 children aged 8–14 years. Construct validity was established by Principal Component Analysis (PCA) of data from 150 school children aged 9–14 years, with an additional examination of gender effects. Discriminant validity of the HLS score was examined in 29 children with Developmental Coordination Disorder (DCD) and 29 typically developing (TD) children. Results The results indicated high internal consistency (α=0.92). The inter-rater reliability was acceptable but indicates the need to refine the scoring instructions. PCA of the five components revealed a one factor solution explaining 61% of the variance. In the discriminant analysis, 86.2% of the children with DCD and 89.7% of the TD children were correctly classified to their groups based on the total HLS score. Conclusions The overall findings suggest that the HLS may be a useful tool to identify poor handwriting legibility, with application across different languages and writing scripts.