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