Multi-criteria group assessment of e-commerce websites based on the new PROSA GDSS method : the case of Poland

Due to the COVID-19 pandemic and lockdowns, the popularity and number of users of e-commerce websites has increased significantly recently. In order to retain new users in the future, e-commerce websites need to develop their quality and constantly monitor it. The problem of assessing the quality of websites is a multi-criteria problem and multi-criteria decision making methods are used in it. Taking into account the need for a consensus of experts or users evaluating the website, the article developed a new multi-criteria group decision making method, called PROSA GDSS (PROmethee for Sustainability Assessment- Group Decision Support System), which allows to reward the consensus of decision makers' preferences and penalize conflicts of preferences. This method was used in the evaluation of e-commerce websites operating on the Polish market that offer the widest range of products. In the course of research works, a wide applicability of the developed method in the problems of group assessment and its broad analytical possibilities was demonstrated. As a result of the research, it has been found that local parties have an established position on the Polish e-commerce market, and parties operating from abroad, and those entering the Polish market, must catch up with the distance that separates them from local tycoons.