# An Agile Approach to Improve the Usability of a Physical Telechabilitation Platform
## 2 Related Research  
In this section, summaries of the most relevant contributions found in the related research publications that served as context for this study are presented, but brief definitions of the heuristic evaluation and cognitive walkthrough are given first. Heuristic evaluation is a usability inspection method that identifies usability problems based on usability principles or heuristics [20]. The cognitive walkthrough is a usability evaluation method in which one or more evaluators work through a set of tasks, ask a set of questionsfrom the perspective of the user, and check if the system design supports the effective accomplishment of the proposed goals [16].  
The authors in References [2; 22] mentioned that it is important, once the usability guidelines are defined, to select the usability attributes to be measured; these are methods and metrics that are best for answering the research questions and objectives from the user interface.  
Furthermore, another study [23] mentioned that a side benefit of performing the cognitive walkthrough was that the technique served as a structured tool for collaboration between the medical partners and the technical partners. However, the authors mentioned that a study which performed the heuristic evaluation separately affected the consistency of the usability evaluation results.  
Other studies [14; 15; 16; 17] have highlighted the advantages of combining heuristic evaluation and cognitive walkthrough. The main advantages that authors mention are the identification of major usability issues, the immediacy of response, the non-intrusive methods, it is inexpensive in respect to time or resources, it can be done in a laboratory setting, it is good for refining requirements, it does not require a fully functional prototype, and thus is applicable to the stages of design, coding, testing, and deployment of the software development lifecycle.  
The authors in References [16; 24; 25] presented the disadvantages of performing a heuristic evaluation and cognitive walkthrough. The disadvantages to consider are: expert variability, evaluators must have experience and adequate knowledge to evaluate the product interface, evaluators may not understand the tasks performed by the product making it difficult to identify usability problems, usability problems are identified without directly giving a solution, limited task applicability, variation on the set of heuristics, and the method is biased by the current mindset of the evaluators.  
Other studies [17; 26] presented the usability evaluation results over prototypes. The advantages considered were that the prototype facilitates the development of future tasks to final users and facilitates the learning and development of an iterative processes. However, the disadvantage was that the online prototype presents only a part of the target platform. The prototype is functional and limited only in terms of colors and interactive elements.  
On the basis of the quantitative results and recommendation of the authors [14; 27], two usability evaluation methods were selected: heuristic evaluation and cognitive walkthrough. Heuristic evaluation is a usability inspection method that identifies usability problems based on usability principles or heuristics [20]. The cognitive walkthrough is a usability evaluation method in which one or more evaluators work through a series of tasks, ask a set of questions from the perspective of the user, and check if the system design supports the effective accomplishment of the proposed goals [16]. Authors [25; 28] recommended the use of a testing technique with a customized instrument and an interview as the inquiry method.  
Most of the previous studies do not systematically present the evolution of usability through an orderly and cyclical process. This study intended to tackle this issue to show that it is possible to improve the usability of telerehabilitation platforms without jeopardizing patient safety.