Developing evaluation scales for horticultural therapy

•Physical, cognitive, psycho-emotional, and social evaluation tools for horticultural therapy were developed.•The four evaluation tools developed were formulated through strict research and analysis methods and procedures, and have proven validity and reliability.•These tools were developed as integrated surveys that can be applied to all age groups, from childhood to old age, and to all types of subjects, both with and without disability. This study developed evaluation scales for measuring the effects of horticultural therapy in practical settings. Qualitative and quantitative research, including three preliminary studies and a main study, were conducted. In the first study, a total of 779 horticultural therapists answered an open-end questionnaire based on 58 items about elements of occupational therapy and seven factors about singularity of horticultural therapy. In the second study, 20 horticultural therapists participated in in-depth interviews. In the third study, a Delphi method was conducted with 24 horticultural therapists to build a model of assessment indexes and ensure the validity. In the final study, the reserve scales were tested by 121 horticultural therapists in their practical settings for 1045 clients, to verify their reliability and validity. Preliminary questions in the effects area of horticultural therapy were developed in the first study, and validity for the components in the second study. In the third study, an expert Delphi survey was conducted as part of content validity verification of the preliminary tool of horticultural therapy for physical, cognitive, psychological-emotional, and social areas. In the final study, the evaluation tool, which verified the construct, convergence, discriminant, and predictive validity and reliability test, was used to finalise the evaluation tool. The effects of horticultural therapy were classified as four different aspects, namely, physical, cognitive, psycho-emotional, and social, based on previous studies on the effects of horticultural therapy. 98 questions in the four aspects were selected as reserve scales. The reliability of each scale was calculated as 0.982 in physical, 0.980 in cognitive, 0.965 in psycho-emotional, and 0.972 in social aspects based on the Cronbach’s test of intra-item internal consistency and half reliability of Spearman-Brown. This study was the first to demonstrate validity and reliability by simultaneously developing four measures of horticultural therapy effectiv