**7. Conclusions**

The contribution of this paper is manifested by the development of a robust methodology of a comparative assessment of the state of transition towards a Circular Economy in given countries with special focus on European Union members. The methodology allows for the determination of the level of a country's relative performance as well as the disclosure of the sources of its inefficiencies. Comparative analysis of this kind, performed on a regular basis according to a unified methodology, may serve as an instrument of refining the CE indicators and improving policy coordination of EU and member states in striving for ambitious CE goals. The paper also aims at promoting DEA applications in measuring relative performance of particular countries in spheres that are subject to common policies.

The results show a strong correlation between CE indicators and a certain degree of sensitivity to slight data changes. Moreover, it is impossible to select a leading country or group of countries superior to others with respect to all studied variables. In consequence, if the proposed approach is ever used to determine the streams of funding to particular EU member states, there exists a risk of manipulating the input variables and input data to serve particular interests. Transparency in this respect will be of critical importance.

The study shows that countries with higher GDP per capita perform better in terms of CE goals. This implies that poorer countries require tailored support measures oriented at the general modernisation of their economies accompanied by an increase in the efficiency of their production factors.

The journey towards a CE is only starting. There is a clear need to develop and refine tools of an objectivised assessment of countries with regards to their progress towards the CE. This paper makes a contribution to this global effort.

**Author Contributions:** J.N. and E.C. were responsible for the study conception and research design; J.N. and Ł.N. developed the concept and carried out the literature review; E.C. performed computation and analysis; J.N. and E.C. were responsible for data interpretation; J.N. and Ł.N. discussed the results and contributed to the final manuscript; J.N., E.C. and Ł.N. wrote and edited the text. All authors have read and agreed to the published version of the manuscript.

**Funding:** The publication of the article for 11th International Conference on Engineering, Project, and Production Management—EPPM2021—was financed in the framework of the contract no. DNK/SN/465770/ 2020 by the Ministry of Science and Higher Education within the 'ExcellentScience' programme.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Publicly available datasets were analysed in this study. These data can be found here: https://ec.europa.eu/eurostat/web/circular-economy/indicators/monitoringframework (accessed on 17 March 2022).

**Conflicts of Interest:** The authors declare no conflict of interest.
