**3. Literature Review and Conceptual Model**

Recent literature reviews on the published works on LSQ have been conducted by Michalski and Montes-Botella [21] and Arabelen and Kaya [9]. Siddh et al. [41] investigated the LSQ of an agri-food supply chain. The pre-defined conceptual model consists of six dimensions and 26 explanatory variables as shown in Table 3. The six dimensions are quality or reliability of customer focus (REL1–REL4), digital transformation (DIG5–DIG8), physical distribution service quality (DSQ9–DSQ13), corporate image (COR14–COR17), sustainability (SUS18–SUS23), and timeliness (TIM24–TIM26). The description of each dimension will be given below.

To measure the quality or reliability of customer focus, the research uses the original SERVQUAL questionnaire. This group of attributes is necessary for focusing on customers in addition to the focus on the attributes of the service itself, as it was proposed in the original questionnaire. These attributes reduce the risk of emphasizing logistics attributes that might not be consistent with what customers really value [21,42,43].


The digital transformation factor aligns with the general definition of digitalization. It commonly encompasses two components: digital implementation of communication and digital conversion of data. Both components are considered to be important for integrating information flows between supply chain stages using particular technologies such as RFID [48], cloud-based solutions such as e-platforms [49], standards such as Electronic Data Interchange (EDI) for Administration, E-Commerce and Transport (EDIFACT), and capabilities to follow the path or current location of a delivery from the starting point to wherever the object currently is in real time. The latter can significantly influence satisfaction as Gil Saura et al. [47] showed in their investigation of the perception of LSQ among 194 Spanish manufacturing companies in a supply chain with high levels of ICT. Furthermore, the use of information and communication technologies (ICT) maximizes farmers' profit and minimizes the product price for consumers [50]. Previous research has shown that the quality of information sharing affects the supply chain food quality performance [51] and that the level of digital transformation is an important competence for coping with dynamic business environments such as COVID-19 [52].

Physical distribution service quality addresses physically observable operational attributes, composed of aspects relating to timeliness, availability, and condition [44]. A favorable and attractive corporate image is central in Grönroos's [45] service quality model. As proposed by Thai [33], it relates to the customers' overall perception of logistics service providers (LSPs) as the company's reputation for reliability in the market, its professionalism and consistency in satisfying customers, its reputation, and its ethical image.

The sustainability factor addresses the social and environmental criteria. A comparison of six reporting initiatives on sustainability [46] shows that efficient use of resources and climate change mitigation are most frequently included in the environmental dimension. The proposed model does not encompass measures for the economic dimension, but environmentally friendly supply chain practices are relevant to the operational and financial performance, as the analysis of 232 LSPs shows [53]. Social sustainability is measured through labor practices in all six initiatives [46] such as employees' training and human safety, and social responsibility. Furthermore, engagement in community activities, the availability of a performance statement, and a vision for community responsibility address the stakeholder concept [31] and round off the sustainability factor.

The timeliness factor encompasses three time-related issues including timeliness of shipment pickup and delivery, transportation time, and the reliability of the total order cycle time. The timeliness factor is the most significant dimension for LSQ in many logistics studies [33,47].
