# Key Performance Indicators for Food Supply Chain: A Bibliometric and Systematic Literature Review
## 3 Results
### Outcomes of the Statistical Analyses  
It is useful to point out that, for completeness, the final sample of papers (125) is fully reported in Table A1 (Appendix A), together with their classification by research methodologies. From the appendix, it is possible to note that empirical studies emerged as the most frequent type of research (68 publications), followed by case studies (43) and analytical models (39). Note that in the same paper, more methodologies could be involved; for instance, an analytical model could be developed and then implemented in a case study. In this case, both categories were assigned to the paper. Moreover, it is interesting to note that empirical studies have appeared in literature with good continuity, with the only exceptions being the years 2003, 2009, and 2010, in which there were no empirical papers. This result is in line with the topic investigated: empirical research normally deals with data collected from real contexts, and KPIs are normally built on data and numbers. This Section is intended as a general overview of the state of the literature that focuses on measuring the performance of FSC by means of KPIs. In Figure 2, the evolution of the yearly number of papers inside the present sample is reported, specifying the type of publications by year. Figure 2: Distribution of publications by year and publication type. The column chart corresponding to the year 2024 is significantly lower if compared to the values reached in the latest years, because the available literature includes papers published before March only (reflecting the time of the query). Nonetheless, as can be seen from the figure above, the general trend observed is that the number of publications is growing. Overall, the statistical data indicate that publication and research in the area of KPIs in FSC increased in the years 2018-2023 (82 papers out of 125, 65.6% of the sample). It should be noted, however, that in general an increase in scientific publications is recorded in almost all the fields related to supply chain issues, above all, after the recent pandemic. Indeed, FSCs have been adversely affected by COVID-19 under different perspectives [32], and thus, numerous studies relating to COVID-19 have precisely targeted the FSC. The sales volume was one of the typical aspects investigated: at the beginning of the pandemic, COVID-19 caused demand and supply uncertainty, with an initial decrease in demand because of the consumers' less frequent store visits and restrictions/limitations to people movements [33; 34]. An opposite effect, instead, was observed later, when the early lockdown measures changed people's purchasing behavior, leading to \"panic\" buying and thus an increase in demand. The perishability of the items, a typical challenge of the FSC, was another typical field of research, because of the additional risk perishability involved in pandemic periods [35]. As can be deduced from the figure above, the sample consists of 100 articles in international journals, including 90 research papers and 10 reviews, and 25 papers published in international conferences. In addition, it is interesting to point out that the first review, dealing with quantitative models for sustainable food logistics management, was published in 2012 [36], while the first conference paper was in the following year [37]. The fact that literature reviews were mostly published in the last years (i.e., two reviews published in 2018; one review per year published in 2019, 2020, 2021, and 2022; two reviews published in 2023) is in line with the fact that literature reviews, to be defined as such, need a certain number of documents on which to focus, meaning that previously a huge number of documents was produced. As far as the journal analysis is concerned, the sample under investigation comes from 100 different sources; among these, 85 (68%) published one paper only. Figure 3 below presents the sources that published at least two papers reviewed in this study.