# Evaluation of Cloud Services: A Fuzzy Multi-Criteria Group Decision Making Method +
## 1 Introduction  
With the rapid development of information and communication technologies and increasing globalization, Cloud computing is becoming popular in which computing infrastructure and solutions are delivered as a service [1]. Clouds are next-generation data-storage and computing systems with virtualization as the core, enabling available technologies to interconnect and manage distributed computers where resources are dynamically provisioned on demand [2]. The use of Clouds greatly helps organizations create and maintain their competitive advantages and improve their overall performance in the marketplace. It often provides organizations with numerous benefits including (a) the reduction of costs in managing and maintaining organizational information systems; (b) increased productivity; (c) improved collaboration; and (d) the flexibility that individual employees seek [3]. The popularity of cloud services results in their proliferation in the marketplace. As a result, adequately evaluating and selecting the most appropriate Cloud service in a specific situation with respect to specific user requirements has become a significant challenge for decision makers in various organizations [1; 3]. Often, there are various trade-offs between different user requirements that can be accommodated by various Cloud services. This makes it difficult to evaluate the overall appropriateness of available Cloud services for implementation in a given situation. Evaluating the performance of Cloud services for implementation in an organization is complex and challenging. This is due to (a) the involvement of multiple decision makers in evaluating the appropriateness of available Cloud services with respect to multiple, often conflicting criteria; (b) thepresence of subjectivity and imprecision inherent in the evaluation process [2]; and (c) the need to adequately consider the interest of multiple decision makers in a comprehensive manner. Much research has been done on the development of numerous methods for dealing with the Cloud service performance evaluation and selection problem [3; 4; 5; 6]. [PERSON] et al. [3], for example, use analytic hierarchy process to evaluate the performance of Cloud services in an organization. This process consists of three steps including (a) problem decomposition; (b) priority judgment; and (c) priority aggregation. In problem decomposition, a hierarchy structure of problem evaluation is developed for describing the relationship between the goal of the Cloud service selection, the evaluation criteria, and the available Cloud services. In the priority judgment, pairwise comparisons are conducted to determine the relative importance of the criteria and the performance of the Cloud service. In the priority aggregation, the overall rankings of these Cloud services across all the evaluation criteria are determined based on the aggregation of the priority judgments in the second phase along the utility theory in a specific situation. [PERSON] and [PERSON] [5] apply the simple additive weighting (SAW) method for dealing with the Cloud service performance evaluation and selection problem. A Delphi method is used to assess the relative importance of each criterion through an expert interview. The SAW method is then employed to determine the overall performance of each alternative across all the criteria on which the ranking of the Cloud service is determined. [PERSON] et al. [6] present an integrated method using the analytic network process (ANP) and zero-one goal programming for evaluating the performance of Cloud services. ANP is used to calculate the weightings for the evaluation and selection criteria. The information obtained from the ANP is then used in the zero-one goal programming for determining the overall ranking of the available Cloud services. The methods discussed above have shown their applicability in solving various Cloud services' evaluation and selection problems from different perspectives under various circumstances.