The era of knowledge and technology has invigorated people’s social, educational, and organizational environments, forcing institutions to re-formulate their strategies to provide accurate quality responses to the environmental demands. The field of education has not been the exception, making room for new and varied forms of non-face-to-face education such as virtual education [1] and face-to-face education through electronic learning (e-learning). Learning during the COVID-19 outbreak has gone from a complementary methodology to a mandatory model ^[2][3][2,3] in education, becoming a challenge in many institutions due to the short time to adapt to the pedagogical process, added to the technical, academic, and communication difficulties caused by the pandemic [4]. In this sense, educational and business institutions must improve and ensure the quality of their service to achieve a competitive advantage by providing value to students and society as a beneficiary.

Quality education is established as an integral element of Education for Sustainable Development (ESD) [5]. ESD promotes sustainable development [5] that seeks to eradicate poverty and to promote economic prosperity, social inclusion, environmental sustainability, peace, and good governance for all. In 2015, the United Nations adopted the 2030 Agenda for Sustainable Development [6]. This agenda established 17 Sustainable Development Goals (SDGs), whose aspiration for 2030 was to place the world and its societies on a path towards a better future [6]. The importance of education for sustainable development is recognized in SDG-4: Quality Education [7], which aims to “Ensure inclusive and equitable quality education and promote lifelong learning opportunities for all”. Quality education contributes to better results in the development of people, as well as their communities [7].

E-learning and information and communication technologies (ICTs) contribute to the SDGs, specifically SDG-4, by promoting virtual or non-face-to-face education. Through ICTs, students can have access to learning resources anywhere and at any time. Teachers can deliver training and can facilitate interactive tutoring virtually. Thus, breaking down economic, social and cultural barriers [8].

From the point of view of e-learning, the term “quality assurance” does not have a commonly accepted definition ^[9][10][11][9,10,11]; however, Vagarinho [10] defines it from the compilation of 24 characteristics grouped into four areas (learning platform, improvement, skills, and sustainability) that must be met. On the other hand, Marciniak [9] defines it as the process of striving to achieve the dimensions that make up the quality of virtual education and indicators associated with them; Duque [7] refers to it as the fulfillment of requirements, the satisfaction of customer needs and as a competitive strategy. From these definitions and those referred to in each study mentioned above, quality itself can be defined as the characterization given to a product, in this case, virtual education, in line with the needs expected by the user. The client, whether they are a student, a teacher, society, or the government, is considered a fundamental pillar of the management of training institutions to achieve excellence. Therefore, quality assurance must necessarily be evaluated from two main aspects: (a) the quality properties that virtual education possesses and (b) the value judgment given to these properties; that is to say, in a virtual environment, not only the evidence of the aspects that it possesses must be demonstrated, but also the usefulness of these properties [11] and the teaching–learning process itself should be supported by evidence.

There are many standards, models, and regulations as quality characterization instruments. When reviewing the literature, it is evident that many studies highlight the importance of quality in training or virtual education [12]. From there, new models are proposed, or existing methodologies are applied to assess the quality of training at different levels. These could be at the level of institution, program or study, career, virtual education platform, or a particular course [9]. Authors such as Hilera and Hoya [13] compile and highlight in their research ten e-learning quality standards and models that they denote since 1999, showing an interest in quality for approximately two decades.

The primary regulations referenced, which several proposals for new models take as a baseline, are from the ESG (Standards and Guidelines for Quality Assurance in the European Higher Education Area) [14], from which essential standards stand out [15]: (a) quality assurance policies, (b) program design and approval, (c) student-centered learning, teaching, and assessment, (d) student admission, (e) teaching staff, (f) learning resources (includes accessibility of materials and the e-learning system), student support, (g) information management, (h) public information, (i) continuous monitoring and periodic review of programs, and (j) external quality assurance.

The terms evaluation and self-evaluation have a connotation of quality verification. Those responsible for the guarantee, as mentioned above, and the quality control are local governments, quality assurance agencies, institutional management bodies, and the universities themselves as institutions with social responsibility [16]. A self-assessment process, by its essence, is a participatory process of quality management, which is supported by a defined standard or pattern (self-assessment model) to establish the strengths, weaknesses, and improvement plans that pursue a continuous assurance of quality [17].

Addressing quality from an accessibility and inclusion perspective is also a challenge and, in turn, a necessity for virtual education institutions since, for a long time, the importance of accessibility or the limited approach with which virtual education is conceived has been minimized. There has been a misconception of accessibility as simply having an accessible website, or even a lack of knowledge of accessibility. Kumar and Owston [18] proposed e-learning accessibility based on the e-learning platform’s accessibility and evaluated it from two methods: compliance tests (such as compliance with the WCAG) and user tests or usability tests to identify accessibility barriers. Seale [19] proposed accessibility in e-learning from a holistic view, which started from a conceptualization and study of disabilities and, in addition to the accessibility of the platform, considered elements such as institutional policies, support, and assistance to students and teachers with disabilities, as well as assistive technologies in other aspects.

Other studies reveal the need to rethink the universal learning design to better adapt to students with disabilities since it is not enough to have an accessible LMS (learning management system). Still, curricular adaptations are required to help these students [20]. All of this confirms the importance of accessibility in e-learning, placing accessibility as a transversal component in the quality of virtual education [21].

To achieve the SDG-4 [22], education must be of quality and must be accessible, in the sense of accessibility described above. In this way, based on accessibility, it will be possible to move towards sustainability in online education that uses primarily web-based technology, because accessible education gives people with disabilities the opportunity to learn in equal conditions [23], but web accessibility is also good for the planet because some of the flagship good practices in accessibility can reduce the carbon footprint of a website [24].

2. Quality Assurance in E-Learning

Quality and accessible education for everybody could expand the scale of students who access it and, thus, support education for sustainable development (ESD) ^[25][34]. In this way, it is expected to achieve the sustainable development goals (SDGs) since no goal is attained without the education sector ^[25][26][34,35]. Equitable and greater access to quality education contributes significantly to the fourth SDG, an objective that through its 10 goals focuses on guaranteeing equitable and quality access for all children to primary and secondary education, as well as guaranteeing equitable access for all women and men to quality technical, vocational, and higher education, including university education, without discrimination, seeking to increase the number of people who have the necessary skills (technical and professional), to access employment and decent work [22]. This research aimed to propose a self-assessment guide for the quality of e-learning from accessibility. Accessibility is conceived of as an opportunity within education services and the use of ICT ^[27][36], which thwe researchers sstarted from a study referring to quality assurance in e-learning to build a solid knowledge base around the subject. In particular, the proposed self-assessment guide contemplates a set of actions that can contribute to the SDGs, these being: (a) ensure access and participate fully in the university for vulnerable and disadvantaged people, including people with disabilities, indigenous peoples and people with economic difficulties, (b) providing facilities that promote and encourage inclusivity in learning [7]. Here shows a growing interest in quality assurance in virtual education. For example, there are proposals for new models such as those described in ^[28][29][37,38] and proposals based on existing models, which result from adaptations focused on specific needs ^{[30][31][32][33][34][35][36][37][38]}[27,39,40,41,42,43,44,45,46]. Countries such as Colombia ^[39][30], Costa Rica ^[40][32], Mexico ^[41][31], Ecuador ^[42][47], among others, have quality accreditation institutions based on their evaluation models; this is also true of international organizations, such as the European Union [14]. In addition, comparative analyses and compilations of known quality assessment models and standards relevant to the authors of certain studies can be identified in the literature ^{[9][12][43][44][45][46]}[9,12,48,49,50,51]. Other studies have also aimed to propose aspects or recommendations for adaptations to new models ^[47][48][49][52,53,54]. During the literature review, it was noted that the scope of application or evaluation area differed between models. For example, there are models of institutional evaluation ^{[50][28][29][33][34][51]}[33,37,38,41,42,55], others for the assessment of the program ^{[3][9][31][52][53]}[3,9,39,56,57], or of a course ^[54][55][56][28,58,59], evaluation of the platform (LMS) ^[31][39], evaluation of teaching ^[30][27], or e-assessment ^[32][37][40,45]. This revealed that the quality assessment around training in virtual education can range from general to specific such as e-assessment. In this sense, the guide proposed in this study has flexible applicability at different levels (institutional, training program, particular course). Likewise, based on the application approaches identified in each model, it is evident that an evaluation model is not generalizable, since it often responds to sociocultural and particular needs of sectors, countries, or regions ^[39][41][40][30,31,32]; For example, four studies ^{[30][50][36][57]}[27,33,44,60] presented proposals for models whose approach, according to the authors, is specific for application in universities or training institutions in the European Union. Likewise, four models ^{[28][29][31][58]}[37,38,39,61] focused their criteria on the context of developing countries. In addition, only one study ^[59][29] considered the sociocultural context and particularities of the countries that make up the Latin American region and the Caribbean countries. Considering this fact, the guide includes a refinement phase of the model to the local context.