# Multidimensional Study on Users' Evaluation of the KRAKEN Personal Data Sharing Platform
## 4 Discussion  
This study presents a multidimensional evaluation of the KRAKEN personal data sharing platform, tested by 15 individuals representing key target user groups of the platform in the health and education pilot domains. Our main findings show that the usability of the prototyped platform was perceived by users as marginally acceptable but requiring further improvements before its final release. The importance of the usability dimension was also stressed by participants during the online group interviews, where most of them expressed interest and trust in using the data sharing solution, both as providers and consumers of data products, if the user experience ensured is good, and the security and privacy preserving components of the platform, including its privacy preserving analytics, are clearly presented to the user. This finding confirms previous research in showing that there could be barriers to the adoption of blockchain-based data sharing platforms, if the security and privacy preserving mechanisms provided are not fully transparent and understandable by the user [2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14]. Regarding the sharing of health or education data through the platform, most of our participants expressed a preference for sharing data for research or non-profit purposes, while they were less inclined to share data for commercial reasons. Our findings are aligned with previous work showing that factors such as specification of the end purpose for sharing data [7], as well as the possibility of revoking access to shared data products [25] or setting privacy policies to access data, are key capabilities enabled by blockchain-based platforms that may meet the needs and preferences of users and positively affect future adoption. Concerning the possible incentives to users for sharing data products, our findings suggest that participants were interested in receiving either monetary or nonmonetary forms of compensation. Nonmonetary compensation seems to be particularly relevant to data sharing in the health and education domains, where altruistic reasons for sharing data products may be key drivers of a system's adoption and user engagement [2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26]. Our investigation into the possible user concerns regarding the ethics dimension of using the platform revealed that the participants need for being supported at the point of taking key decisions affects the creation or sharing of a data product, for example, by being reminded about possible consequences of their action, and helped in understanding and revising the related privacy or ethics issues. All these considerations should inform the user-centered design of a data sharing platform such as KRAKEN to better fit the needs and expectations of its future adopters, as well as to ensure a more functional coevolution of its technical capabilities with user preferences and behaviors. The study presented has some limitations. The sample size is rather small and participants involved in the health pilot belonged mainly to the research field, while those involved in the education pilot represented mainly the perspective of data providers rather than that of data consumers. In a future evaluation study, we intend to recruit a larger and more diversified sample of participants to better represent the broader target population. Moreover, the set of technical capabilities offered by the KRAKEN prototype deployed in this study was quite limited, and participants were asked to test the platform with sample data products created for evaluation purposes. Future studies may investigate more in depth the users' preferences and concerns of users when conducting transactions on real data products over more mature and complete versions of data sharing platforms.