## 4 Results
### The Challenges of Including Users with Disabilities in User-Based Testing
\begin{table}
\begin{tabular}{p{42.7 pt} p{284.5 pt} p{284.5 pt}} \hline \hline
**ID** & **Challenges** & **Short Explanation** \\ \hline \multicolumn{3}{p{42.7 pt}}{C1. Challenges before user testing} \\ \hline \multirow{3}{*}{C1.1} & Selecting participants without bias & A common type of bias in participant selection is sampling bias. Bias in participant selection can lead to testing results that do not accurately represent the needs and preferences of the targeted user group. Selecting participants with prior interest or knowledge about the tested solution can also impact user testing results [36]. \\ \hline \multirow{3}{*}{C1.2} & Understanding participants characteristics, needs, and cultural and personal differences & Planning user-based testing, especially with users with disabilities, can be challenged by a poor understanding of cultural and personal differences. Researchers do not understand the specific needs and mindsets of users, both with and without disabilities [37]. Users with disabilities may communicate in different ways or require assistive products. Consequently, the user-based testing processes for users with disabilities are not properly designed and executed. For example, if international user testing participants are included, disregarding cultural differences is problematic [38]. \\ \hline \multirow{3}{*}{C1.3} & Developing protocols for enabling inclusive user-based testing & The design of an inclusive test protocol requires understanding protocol differences for users without disabilities and users with disabilities. Users with disabilities may have different capabilities and limitations, which in turn can affect their ability to participate in tasks that demand physical activity or cognitive load. Due to individual differences in capabilities between different users, results cannot be directly compared [39]. \\ \hline \multirow{3}{*}{C1.4} & Preparing tasks suited to the participants’ ability & In user-based testing, where users must complete different tasks, it is essential to prepare tasks that suit users’ abilities. For example, participants with intellectual disabilities have difficulties completing complex tasks [40], and for such users preparing tasks aligned with their cognitive effort abilities is critical. \\ \hline \multirow{3}{*}{C1.5} & Setting up the testing environment according to the specific user needs & The successful implementation of user testing also depends on a properly prepared test environment, which, especially in the case of users with disabilities, must be adapted to the abilities, needs, and other characteristics of the users. Difficulties can occur when setting up the testing environment for each participant with disabilities [41] because different disabilities require different accommodations. \\ \hline \multicolumn{3}{p{42.7 pt}}{C2. Challenges during user testing} \\ \hline \multirow{3}{*}{C2.1} & Getting used to and learning how to use the product by users & The users need help accustoming to the tools or Uis they use for the first time during the testing process [42]. For example, older adults and users with disabilities struggle to use unfamiliar tools [43], which can add additional time and effort to the testing process. This challenge is connected to a variety of factors including the complexity of the UI, the lack of familiarity with the UI, the lack of clear instructions or guidance on how to use the UI effectively, the user’s confidence in using the UI, and the time pressure or the need to complete tasks quickly, which can further increase the difficulty of learning and adapting to new tools. \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Challenges of including users with disabilities in user-based testing.