This section will provide an overview of the necessary literature. As the main topics (closed-loop quality management and customer loyalty measurement) are usually discussed separately in relevant references, this review is also divided into two subsections.
3.1. Literature Review Related to the Closed-Loop Quality Management
Key milestones of previous quality evolution, from quality inspection to organisational excellence, were described many times [
9,
10,
11]. However, the prospects for the future of quality management are not quite clear. Let us make a brief preview of some relevant opinions. Radziwill [
12] considers the future of quality management as a revolutionary matter. R.G. McGrath [
13] perceives future organisations as vehicles for creating complete and meaningful experiences, based on comprehensive customer voicing. Sundaram [
14] presented the results of representative research in manufacturing companies, which was published by Frost & Sullivan: “Industrial producers will do well to probe into innovative technologies and tools that can help integrate customer operations into their systems and, concurrently, help improve process efficiencies, bring down production costs and boost factory performance. To achieve this, manufacturing organisations are making strategic investments in quality management solutions.” In addition, the belief of organisations that traditional quality management systems are increasingly making a move towards a more future-ready and closed-loop approach is expressed there. Most of the current trends of quality management should be adapted to Industry 4.0 environment. For example, Cattaneo et al. [
15] describe how lean thinking should be implemented in the context of a smart factory, and the findings confirm that quality management principles and approaches have a strong potential for supporting a company’s digitalisation initiative [
16].
The term “closed-loop quality management” is discussed in special journal articles as well as in the online environment. However, there is no consensus, which can be taken as clear proof that this field is under progress. The following references provide evidence of it. Littlefield [
17] explains how to understand this term: “Closed-loop quality management essentially means connecting quality process or performance data from one area to another, always with the goal of improving quality earlier.” He also describes two main areas of such an approach: manufacturing and suppliers. The role of closed-loop quality management at manufacturing processes was explored by special LNS research activities [
18], where impacts to the value chain, statistical process control, risk management, complaint handling, and other activities were investigated. The closed-loop approach should be looked upon also as a chance for supplier´s development [
19]. Nikolaidis [
20] emphasizes an important improvement of mutual communication and data exchange between consumers and suppliers. The application of the closed-loop principle in the relationship between consumer and supplier, the so-called “closed-loop supply management,” is described by Almaraj and Trafalis [
21] and many other authors.
Goulévitch [
22] provides eight examples of how closed-loop quality management systems should work, including transparency in production processes, traceability, integration with ERP systems, facilitation of lean processes, etc. However, the most convincing facts about the necessity to design and develop closed-loop quality management were brought by special investigations performed by members of Aberdeen Group and published by Littlefield and Shah [
23]: A lot of data on how to shift from laggard or industry average performance to the best-in-class through feedback loops are conclusively presented there. M. Sony et al. [
24] distinguish three forms of integration within closed-loop quality management in the Quality 4.0 era:
- -
horizontal (which is along the entire value creation chain),
- -
vertical (which is alongside the organisation´s system),
- -
end-to-end (along the product life cycle).
Foidl and Felderer [
25] see horizontal, vertical, and end-to-end forms of integration as important topics for the further research.
On the basis of this brief literature review, it is possible to generalize some provisional conclusions in the area of closed-loop quality management:
- (a)
The closed-loop quality management is considered as a “must have” future approach to quality management development in all organisations.
- (b)
There is no available exact terminology related to closed-loop quality management area as a result of expert consensus.
- (c)
The most frequent investigations and practical implementations of closed-loop approach cover internal production processes, with the aim to improve processes capability.
- (d)
There is only a limited set of data focused on the cost–benefit analysis of closed-loop quality management initiatives at present.
- (e)
The closed-loop quality management does not reject traditional and proven quality management methods and tools. On the contrary, it enriches them with the advantages and possibilities of the digital era.
- (f)
Development of closed-loop quality management systems is under progress all over the world.
- (g)
Information about external loops based on customer loyalty measurement, monitoring, and communication as a part of closed-loop quality management is completely lacking.
In particular, insufficient establishing of the closed-loop quality management systems as a combination of internal, external, horizontal, and vertical loops (taking into consideration feedback loops from customers) represents a research gap as well as an opportunity for further research.
3.2. Literature Review Related to Customer Loyalty Measurement (with Respect to Sustainability)
Recent research conducted by Sisodia and Forero [
26] on how to transition into Quality 4.0 has proposed (among other things) a road map for this transition. Special phases of this road map emphasize all stakeholders’ involvement, including customers.
First of all, a core term, “customer loyalty,” should be explained. Hayes [
27] defined this term as follows: “customer loyalty is a twofold customer behaviour resulting in an effective continuation and development of a business relationship in the one hand and in the recommendation of the supplier, its brand, products or services to any potential customer on the other hand.” Watson [
28] says that customer loyalty is a collection of attitudes aligned with a series of purchase behaviours that systematically favour one entity over competing entities. However, customer loyalty is more than just behaviour or repeated business. It also represents a positive level of customer commitment to suppliers. Many authors have started their serious discussions about customer loyalty (including relationships between customer satisfaction and customer loyalty) in the 1990s, when clear evidence appeared, saying that, in spite of the high level of customer satisfaction, a lot of organisations suffered a serious market loss [
29,
30,
31,
32,
33,
34,
35]. The first remarks related to customer loyalty have been already published in Czech Republic in 2001 [
36]. In addition, a clear link between efficient quality management and customer loyalty was confirmed [
37]. Some authors discuss the influence of various factors on customer loyalty, including the relationship between customer satisfaction and loyalty; [
38,
39,
40,
41] represent good examples. The indisputable relationship between customer loyalty and overall supplier performance was investigated and confirmed by Reinartz & Kumar [
42].
Most of customer loyalty studies have focused on services, which are typical for B2C areas [
43,
44,
45,
46]. Only a limited number of papers are dedicated to customer behaviour in B2B area, where customers are not individuals but other units within the whole supply chain, usually purchasing companies. Except for the article of Rauyruen & Miller [
37], let us mention Bardauskaite [
47], first of all, who analysed very closely some papers and articles and identified the main loyalty determinants in B2B service context. Some findings related to power of The European Customer Satisfaction Index (ECSI) model were presented by Askariazad & Babakhani [
48]. An interesting study published by Russo et al. [
49], where different configurations of costs, returns management, customer value, and customer satisfaction were analysed in order to approve a close relation to the customer’s future behaviour, is also impressive. A multidimensional construct, the customer engagement with three dimensions, cognitive, emotional, and behavioural, was described as a prerequisite for customer loyalty in B2B area by Youssef´s team [
50]. Unfortunately, standards such as ISO 9001:2015 [
51] or ISO 9004:2018 [
52] do not mention the term customer loyalty at all. This absence must be considered as a serious weakness of these documents. Therefore, a short quotation cited from [
53], “Studying and understanding customer’s loyalty is crucial in today’s dynamic world due to changing technology, contexts, and lifestyles,” can serve as a convenient umbrella statement at this moment.
When discussing some quality management or customer loyalty issues, impact on and relationships to sustainability must not be ignored. Quality management principles and product development activities can make sustainability more actionable [
54]. Nguyen, Phan, and Matsui [
55] established four quality management processes that have significant and positive impact on sustainability performance: top management support, design for quality, quality data reporting, and continuous improvement. Although their investigations were carried out in Vietnamese companies, experience has shown that these findings could be understood as universal. An important set of data must come from customer feedback. Veldwijk [
56] declares that more than two-thirds of consumers consider sustainability when purchasing, and 47% of consumers would pay more for a sustainable product. Garai [
57] presents four benefits of sustainability in loyalty programs: more in-store visits, larger community, reduced production, and greater social engagement. He supports them by examples from some companies. J. Weinberg [
58] offers similar information and shows three factors that lead to the fact that sustainability is increasingly becoming a major consideration for a growing number of customers: the strengthening acceptance of climate change, a strong resolve to take action regarding sustainability from the youth segment of customers, and increased importance of the feelings associated with making sustainable choices. Some authors (Siva et al. [
59], for example) argue that customer focus strongly supports approaches to sustainable development. Brunet and Llach [
60] bring interesting findings related to the promotion of a sustainable economy through reducing the consumption of new products.
It seems to be clear that a feature usually called corporate sustainability ought to be focused with respect to future customer’s behaviour—findings published by Strenitzerova and Gaňa [
61] are evidence of relationship between them.
Corporate sustainability is an important part of the overall sustainability area. According to the Dow Jones Sustainability Index [
62], corporate sustainability is a business approach that creates long-term shareholder value by embracing opportunities and managing risks deriving from economic, environment, and social development. Considering this definition, corporate sustainability can be seen as interwoven with the concept of corporate social responsibility: this concept was based on the idea of sustainability, and it recommends what different organisations should do to reach a high level of sustainable development. The definition of corporate social responsibility from ISO 26000 standard [
63] is quite conclusive: “The responsibility of an organisation for the impacts of its decisions and activities on society and the environment, resulting in ethical behaviour and transparency which contributes to sustainable development, including the health and well-being of society; taken into account the expectations of stakeholders; complies with current laws and is consistent with international standards of behaviour; and is integrated throughout the organisation and implemented in its relations.” A set of facts that significantly confirm the strong and positive link between corporate social responsibility and customer loyalty, regardless the branch and business, was brought by [
64,
65,
66,
67].
On the basis of this review, the following general conclusions should be identified in the area of customer loyalty measurement (with respect to sustainability):
- (a)
Customer satisfaction measurement (required by ISO 9001:2015 or IATF 16949:2016 standards) is currently not sufficient.
- (b)
Unlike customer satisfaction, which only provides past view, customer loyalty offers a glimpse into the future.
- (c)
All fundamental loyalty determinants and factors have been already identified by many authors and loyalty models.
- (d)
The majority of such models, including indicators, are usually tailored for commercial services in advance.
- (e)
Only a limited number of investigations focused on approaches and methodologies of customer loyalty measurement in B2B manufacturing context, including automotive industry.
- (f)
Perceptions of social, environmental, and economic issues of sustainability influence future customer behaviour and their level of loyalty.
- (g)
Socially responsible consumers will be loyal only if the suppliers are able to meet requirements regarding to sustainable products and service.
- (h)
Customer loyalty measurement and monitoring should be an important part of strategic management in all types of organisations.
- (i)
In B2B area, approaches and methods of customer loyalty measurement that very often operate within complex supply chains must respect all specific features of mutual relationship between suppliers and consumers.
- (j)
Closed-loop quality management systems will serve as an effective basis for such measurement.
How to integrate customer loyalty measurement into closed-loop quality management systems based on combinations of internal, external, horizontal, and vertical loops represents another research gap. This statement complies with the suggestions of Sader et al. [
68], who argue that direct communication of customers´ expectations and perceptions is one of the serious topics of further research. Additionally, Goecks et al. [
69] confirm, on the basis of literature review, that all decision-makings within quality management systems must be supported by objective input data. They see this fact as another research gap.
The proposed framework and indicators (which is described in the following section) will try to take all these issues into consideration.