Making transparency transparent: a systematic literature review to define and frame supply chain transparency in the context of sustainability

For literature reviews, it is crucial to have a material selection process that is “objective, valid and reliable” (Hochrein et al. 2015, p. 256). In order to do so, clear rules to include and exclude articles were established for each step. In the case of uncertainty regarding individual articles, they were discussed with two experts in the field of sustainability and supply chains at multiple meetings during the development process. The inclusion/exclusion criteria and the expert consultation ensured a consistent selection process. This procedure is recommended for studies conducted by a single researcher (Hochrein et al. 2015; King 2004; Nowell et al. 2017).

To identify the relevant articles, two databases were selected: Scopus and the Web of Science. As in previous studies (e.g., Ahi and Searcy 2013; Merino-Saum et al. 2020), the Scopus database was chosen due to its broad coverage of academic journals with economic, environmental, and social orientations. The Web of Science database was also selected due to its wide range of journals. The search was targeted at peer-reviewed articles in the English language at the intersection of transparency, supply chains, and sustainability and included articles published up to the end of 2020. To cover relevant aspects, the following search string was applied: (transparen*) AND (supplier OR “commodity chain” OR “supply chain” OR “demand chain” OR “value chain”) AND (sustain* OR social OR environment* OR ecological*) using “Title-Abstract-Keywords” as the search category. The search resulted in 614 articles in Scopus and 219 articles in the Web of Science database. After eliminating duplicates, 645 distinct articles remained. As a common next step in systematic literature reviews, the articles were screened by title and abstract (e.g., Garcia-Torres et al. 2019). When an article did not address both sustainability and supply chain transparency, it was eliminated. Articles eliminated at this stage could be the result of a search criterion term being used in a different context, for example, when “environment” was used to describe surroundings or conditions instead of the natural world with regard to sustainability (e.g., Beulens et al. 2005; Chua et al. 2003) or when “transparency” referred not to supply chains but to a method used (e.g., Badi and Murtagh 2019; Lap et al. 2019). In cases of uncertainty, the abstract was read by another coder in order to generate an inter-rater reliability. The author read the remaining 271 articles in full. As a result, 131 relevant articles were identified. Those articles were identified as treating supply chain transparency as a central aspect or as one of the main aspects in the context of sustainability. According to their main focus on supply chain transparency and the presence of a definition of supply chain transparency, the articles were further divided into four groups. The material collection process, as well as the group classification, is shown in Fig. 2.

As a result of the first research stage, 40 articles with definitions of supply chain transparency were identified (Groups 1 and 3). Articles with definitions included articles with the authors’ own definitions and articles in which the authors cited a definition of transparency. All transparency definitions were analyzed to see how transparency was defined and framed in the context of sustainability in supply chains (RQ1) and as to whether transparency was understood as a multidimensional concept (RQ2).

Mayring (2015) points out that the building of categories is the center of content analysis. The categories can be developed deductively as well as inductively (Mayring 2015). In the current study, to analyze the definitions, an inductive approach was chosen. First, the individual elements of the definitions were coded using the software MAXQDA. After analyzing about half of the definitions, the categories were defined. Three possible dimensions of supply chain transparency were identified: sustainable supply chain information, the involved stakeholders, and the perspective of supply chain transparency (Fig. 8).

Based on the dimensions identified in Stage 2 (as seen in Fig. 1), a framework was developed by verifying and specifying the dimensions on a full-text basis of all 131 of the relevant articles. At this stage, a deductive approach was chosen. To identify the characteristics of each dimension, preliminary considerations were made based on the supply chain transparency definition analysis as well as on other literature. For the first dimension, supply chain information, Gardner et al.’s (2019) classification was used. This classification consisted of six types of supply chain information: traceability, transaction, impact, activity, and effectiveness information. It shows the information needed to improve sustainability in supply chains (Gardner et al. 2019). After about 30 articles had been analyzed, the categories were adapted. The definitions of the categories were adjusted, and two additional categories were identified (see Sect. 3.2.1). The sender and receiver categories of the second dimension involved stakeholder were removed from the definitions, and a further subdivision of the different stakeholders was made based on Freeman (2010). For the third dimension perspective, the characteristics of disclosure and visibility were adopted from Kraft et al. (2020).

The descriptive analysis shows the distribution of the publications per year, the journals where most of the articles were published, and the industry foci of the articles. The reviewed articles were published between 2001 and 2019. Both the total number of relevant articles per year and the number of those containing a transparency definition are shown in Fig. 3. In the final years of the examined period, both numbers increased consistently. The sharp increase in 2020 can be attributed to the technical component considered in the science (e.g., blockchain) in addition to the normal increase of the topic transparency and sustainable supply chain management in general (e.g., Rajeev et al. 2017).

The four journals with the most publications are shown in Fig. 4. The 131 identified articles were published in 79 different journals, showing a wide range of topics concerning supply chain transparency and sustainability. In addition to the five journals shown in Fig. 4, 13 journals published two articles each, while 61 additional journals published only one article each from the sample.

Table 1 shows the industry foci of the articles. While 53 articles did not have an industry focus, two industries were predominant in the context of sustainability and supply chain transparency: the agriculture/food industry and the apparel industry.

One of the goals of this article was to clarify the understanding of supply chain transparency. To do so, definitions of supply chain transparency were analyzed, and the use of supply chain transparency was examined on a full-text basis. Out of the 131 articles identified as relevant in the areas of transparency, sustainability, and supply chains, 40 of the articles defined transparency. As James and Montgomery (2017) have pointed out, there is no consistent understanding of supply chain transparency, meaning different approaches and angles have been taken when different authors use supply chain transparency. Eight articles discussed the meaning of supply chain transparency in the context of sustainability in greater detail (Egels-Zandén et al. 2015; Egels-Zandén and Hansson 2016; Gardner et al. 2019; James and Montgomery 2017; Kraft et al. 2018; Mol 2015; Sodhi and Tang 2019; Wognum et al. 2011) whereas the others provided only brief definitions of supply chain transparency.

From the coded content, three possible dimensions of supply chain transparency could be identified at first, as they appeared in most of the supply chain transparency definitions. These dimensions were sustainable supply chain information, involved stakeholders, and perspective of sustaibable supply chain transparency. An overview of the elements and their frequency of use is given in Table 2. The table also includes an example of the supply chain transparency definition with the respective element for a better understanding.

Based on the analysis of the complete texts, the dimensions of supply chain transparency were able to be verified. Each dimension contributes to different supply chain transparency impacts. Gardner et al. (2019) show the central importance of supply chain information by simply asking: “transparency of what?” (p. 3). They further state the dependency of supply chain information on the impact of supply chain transparency (Gardner et al. 2019). For the second dimension, involved stakeholders, Mol (2015) points to the fact that the impact of transparency can differ based on who is providing information to whom. The impact of supply chain transparency differs as well when looking at the third dimension of either processing information or, from the other side, providing information (Kraft et al. 2018). Each dimension is further elaborated in an individual section below.

As shown in Table 1, the food and fashion industries were the industries most addressed in supply chain transparency research in our sample. This stands in contrast to the findings of Hochrein et al. (2015), who showed that supply chain management research was conducted in a wide field of industries and had no clear focus on specific industries. To address the third research question and therefore show whether supply chain transparency was conceptualized differently among various industries, the use of supply chain transparency in the most frequently mentioned industries was analyzed.

In Table 3, the distribution of the characteristics among the supply chain transparency dimension is shown.

When looking at the food industry, the dimension of supply chain information focused on particular areas:

In most cases, senders and receivers of this information were unspecified supply chain actors and for receivers additonally consumer. The third dimension takes into account the characteristics of visibility and disclosure.

When looking at the apparel industry, most articles focused on disclosure from companies to consumers or the public. The dimension of supply chain information focused on the subcategories of traceability, policy and commitment, impact, and activity (where the last three showed a clear focus on the social aspect of sustainability).

Scandals in recent years in both the food and apparel supply chains have in particular led to increased attention not only in practice but also in research on transparency. External stakeholders have pressured industries for more transparency in order to prevent such scandals in the future. The different characteristics of supply chain transparency among those two industries can be explained by the different characteristics of the problems and injustices of their supply chains. Most of the time, scandals in the food industry affect the end consumer and their health. Examples of scandals include contaminated milk powder in China or the salmonella outbreak from peanuts in the USA leading to sickness and the death of consumers, as addressed by Sun et al. (2017), showing the importance of quality and safety in food supply chains (Bastian and Zentes 2013). This reflects the focus of the articles on production and product information, as well as traceability information.

In contrast to the food industry, the scandals in the apparel industry have mainly affected the workers within the supply chain and not primarily consumers. A frequently mentioned example of a scandal in regard to apparel supply chains is the collapse of the Rana Plaza building (e.g., James and Montgomery 2017). Companies experience pressure from consumers and NGOs to address these issues and improve their supply chains. This explains why supply chain transparency in the context of apparel focuses on the disclosure to consumers and the public of traceability information in addition to impact, policy, and commitment information.

Companies have been increasingly forced to collect and share sustainable supply chain information. This challenges companies in two ways: first, they have to obtain sustainable supply chain information, and additionally, they are confronted with large amounts of data that they have to manage (Montecchi et al. 2019). In order to overcome those challenges and address sustainability in their supply chains, the implementation of digital tools has been discussed in recent years (e.g., Frehe and Teuteberg 2017; Venkatesh et al. 2020). The growing importance of this topic has also been reflected in the research literature. Of the 38 relevant articles in 2020, 16 were concerned with digital tools. There were 11 articles that dealt with blockchain technology (e.g., Guo et al. 2020; Kamble et al. 2020; Venkatesh et al. 2020), three articles were concerned with the IoT (Cui et al. 2020; Jæger and Mishra 2020; Khan et al. 2020), and two articles focused on digital approaches in general (Ebinger and Omondi 2020; Kittipanya-ngam and Tan 2020).

When looking at the three dimensions of sustainable supply chain transparency, it is noticeable that specific aspects of supply chain transparency are taken into account. First, supply chain information is mainly concerned with traceability information (e.g., Makkar and Costa 2020). Second, as mentioned above, the focus on individual actors sharing and receiving information shifts toward the participation of all involved actors in the transfer of supply chain information (e.g., Jæger and Mishra 2020; Kumar et al. 2020; Lahkani et al. 2020), and third, both perspectives of supply chain transparency, disclosure and visibility, are considered (e.g., Ebinger and Omondi 2020).

Many advantages are seen in the technical tools, for example, that the information transfer and processing will be much easier and safer (Ahl et al. 2020) and that activities can be monitored with the help of the tools in order to check effectiveness (Venkatesh et al. 2020), as well as decision-making based on the gained information (Guo et al. 2020). However, the disadvantages of high costs and high effort for the implementation of those tools remain (Venkatesh et al. 2020).

The objective of this research was to draw scholarly attention to the use of the term “supply chain transparency” in the context of sustainability and precise and conscious handling of it in future research. Supply chain transparency as defined here should not be used as a general term. This can be done by adapting definitions of supply chain transparency to the context of the specific research. Those individual definitions should refer to the three dimensions of supply chain transparency and therefore consider what information is disclosed by whom and will be visible to whom. Also, studies should be clear about what information is shared, which supply chain tier is covered, and to what tiers the supply chain information extends. Furthermore, it needs to be taken into account that supply chain transparency is conceptualized differently among industries.

However, a limitation must be acknowledged that the proposed sustainable supply chain transparency framework results from a literature review and thus would benefit from further empirical research. This could be done, for example, through the Delphi method or a multiple case study approach. Nevertheless, once the framework has been tested, verified, and further developed, it can serve as a starting point for further research in the field of sustainable supply chain transparency and sustainable supply chain management.

With the help of the framework, a measurement tool for sustainable supply chain transparency could be developed, which could extend the work of Morgan et al. (2018). Furthermore, the uncertainties of the relationship between supply chain transparency and sustainability can be investigated in depth. An examination could help determine which factors influence the relationship between transparency and sustainability positively or negatively and which do not affect this relationship.

Also, the literature review revealed further shortcomings in sustainable supply chain management research. First, the upstream information flow should be considered, instead of only considering the downstream information flow. Secondly, the existing research was mainly limited to first-tier suppliers (Grimm et al. 2014), so research should go beyond the first tier or acknowledge the difficulties in doing this. Thirdly, the literature review shows that little is known about companies’ internal processes related to supply chain transparency and its management. Future research can focus on supply chain operations in which senders send sustainability-related information. In addition to this topic, future research should consider strategic elements regarding the decision to share some information and keep other information less visible and the effects of outside pressure and the internal response to it.

This research also has several implications for practitioners. Particularly given current political developments, for example, at the European level with the EU taxonomy and in Germany with the Supply Chain Act, the topic of transparency, especially collecting the right sustainable information and the obligation to disclose certain sustainability information, transparency is a very present issue for companies. While the literature review revealed how difficult it is to gain supply chain visibility beyond tier one due to the complexity of supply chains (Stevenson and Cole 2018), companies are increasingly forced to collect and share sustainable supply chain information. The sustainable supply chain transparency framework can function as a guide for companies. First, companies should obtain a clear picture of which sustainable supply chain information (first dimension) the company is forced to reveal or wants to voluntarily disclose (third dimension) to specific stakeholders (second dimension). Secondly, the company needs to identify what required sustainable supply chain information is already visible to them (third dimension) and what information it needs to obtain. While more and more digital tools are being developed to help with the management of information flows in supply chains, the current literature also highlights the major problems with the implementation of those digital tools (Wamba and Queiroz 2020). In addition, the sustainable supply chain transparency framework can be an orientation point in order to configure and extend those digital tools.

While it is important to gain visibility and share sustainable supply chain information with others, it is also essential to use sustainable supply chain information internally to set sustainable goals, take actions to boycott or “buycott” certain suppliers, or to avoid supply chain risks. A clear definition should contribute to solving these transparency-related issues.