**5. Managerial Insights and Conclusions**

The hospital location selection problem is an important issue for big cities with respect to the fact that the location selection problem is influenced by various decision factors and dimensions in the context of technical, environmental, economic, and social aspects. Therefore, a logical analysis of location alternatives considering all criteria will enable policy-makers to better address the location selection problem. The importance of the hospital location selection problem relies on the fact that any consequences from the medical services directly affect the mortality rate in societies. On the other hand, the COVID-19 outbreak, as one of the biggest threats of the last century, spread to most countries in the world. The high number of infected patients and the limited medical resources to treat the patients resulted in healthcare sectors facing many issues. Thus, policy-makers in the healthcare sector suggested establishing temporary hospitals for only patients diagnosed with COVID-19. In this situation, the location selection problem becomes more important than ever due to the critical situation that the health sectors are in.

To show the efficiency of the proposed decision support framework, we performed a case study using Istanbul, which is one of the world's biggest cities with more than 15 million people. Results indicated that the Beykoz and Bakırköy districts are the most suitable locations for the establishment of a temporary hospital for COVID-19 patients. The populations of Beykoz and Bakırköy districts are very close together. However, the population density in Bakırköy is 7734 per km<sup>2</sup> , whereas the same parameter for Beykoz is only 800 per km<sup>2</sup> . The distance from industrial and production areas is greater for Beykoz than Bakırköy. In addition, the traffic congestion in Beykoz is way lower than in Bakırköy. On the other hand, Bakırköy is one of the closest districts to local and international airports, which can be used to deliver patients that are being transported using air medical services. The establishment of a temporary hospital in Beykoz would also benefit this district in the future. With a high future expansion potential, a big hospital in this area would play a great role in its gentrification. In other words, transportation factors and the applicability of the area will improve, which would certainly bring more profit and satisfaction for all stakeholders in the healthcare sector.

In this paper, we addressed the location selection problem for a temporary hospital in the era of the COVID-19 outbreak. A gray-based decision support framework was presented for the decision-making process, considering the uncertain nature of the information related to location alternatives. The CRITIC and CoCoSo methods were implemented under gray values to determine the weights of criteria and to prioritize the location alternatives, respectively. For a case study in Istanbul, we selected five possible districts for the establishment of a temporary hospital in Istanbul.

Some future research directions can be identified. One may use the proposed decision support framework for the location selection problem in other industries such as waste management, hotels, power plants, airports, and so on. In another direction, one may implement the proposed decision-making approach with other uncertainty models such as fuzzy set theory, rough numbers, neutrosophic sets, etc.

**Author Contributions:** Main idea, conceptualization, supervision, editing, and writing-original by S.H.Z.; Methodology, supervision, editing, and writing-original by M.Y., main idea, case study, methodology, and writing-original by A.E.T., Literature review, general background review, and writing-original by A.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

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