# Key Performance Indicators for Food Supply Chain: A Bibliometric and Systematic Literature Review
## 3 Results
### Outcomes of the Keyword Analysis  
As far as the keywords analysis is concerned, firstly note that 11 publications lacked the author's keywords and were obviously excluded from this elaboration. The keywords retrieved from the remaining 114 papers initially returned 576 different terms. After having adjusted synonyms, acronyms, and spelling, the final list includes 343 terms. According to [72] and as anticipated earlier, keywords were classified according to two different parameters, i.e., frequency and persistence, describing the number of occurrences of a concept over time and its continuity in time. Table 5 shows the distribution of the keywords according to those parameters; from that table, it is immediate to note that most of the keywords (250, 72.8%) were used only once by authors, and thus are expected to describe very specific (niche) concepts. In aggregated analyses, these terms will be excluded, for a more effective representation of the outcomes. By mapping those terms having frequency \(\geq\)4, 20 keywords were recorded, whose distribution in time is shown in Figure 5.  
The representation above indicates that \"Key Performance Indicators\" is the most frequent keyword (33 papers). This result is confirmed by the fact that this general term was used to run all the queries and was, therefore, expected to be among the keywords most frequently observed. \"Supply chain management\" and \"Performance\" take the second and third positions with frequency of 17 and 14, respectively--which again could be expected. Sustainability emerges (with 13 occurrences), suggesting that quite often KPIs could be involved in measuring sustainability-related parameters, in line with what has been observed for the journal analysis; for \"Energy efficiency\" (5) and \"Food waste\" (5, again) similar considerations can be made. \begin{table}
\begin{tabular}{c c c c} \hline
**Author** & **No. of Papers** & **References** & **Citations** \\ \hline [PERSON] & & [36] & 85 \\ J.G.A.J. & 4 & [65] & 36 \\  & & [56] & 206 \\  & & [66] & 8 \\ \hline  & & [45] & 26 \\ [PERSON]. & 3 & [67] & 32 \\  & & [19] & 8 \\ \hline  & & [68] & 2 \\ [PERSON]. & 3 & [69] & 0 \\  & & [23] & 0 \\ \hline  & & [70] & 22 \\ [PERSON]. & 3 & [37] & 3 \\  & & [71] & 7 \\ \hline \end{tabular}
\end{table} 
Table 4: Top authors. Using the detailed data of frequency and persistence for the whole timespan of analysis, the keywords were classified into the four groups mentioned in Section 2.2.2, after setting the following boundaries:  
* Persistence: half of the timespan covered by the 114 studies, i.e., \[\text{Persistence}=(2024-2003)/2=10.50\] (1)
* Frequency: median value of the observations, i.e., \[\text{Frequency}=3.51\] (2)  
The results of the classification are detailed in Table 6; for a more effective representation, the outcomes are limited to those keywords with frequency \(\geq\)2 (88 selected terms). Figure 5: Most frequently used keywords. \begin{table}
\begin{tabular}{c c c c} \hline
**Frequency Count** & **N\({}^{\circ}\) of Keywords** & **Persistency Count** & **N\({}^{\circ}\) of Keywords** \\ \hline
1 & 250 & 1 & 9 \\
2 & 57 & 2 & 47 \\
3 & 16 & 3 & 65 \\
4 & 6 & 4 & 23 \\
5 & 5 & 5 & 17 \\
6 & 1 & 6 & 25 \\
7 & 2 & 7 & 28 \\
9 & 2 & 8 & 17 \\
13 & 1 & 9 & 14 \\
14 & 1 & 10 & 5 \\
17 & 1 & 11 & 14 \\
33 & 1 & 12 & 23 \\ - & - & 13 & 17 \\ - & - & 15 & 7 \\ - & - & 16 & 4 \\ - & - & 17 & 14 \\ - & - & 19 & 8 \\ - & - & 22 & 6 \\ \hline Total & 343 & Total & 343 \\ \hline \end{tabular}
\end{table} 
Table 5: Number of keywords by frequency and persistency. As can be seen from the table above, most of the core concepts, as again expected, reflect those shown earlier in Figure 5, and include, among others, \"Key performance indicator\", \"Supply chain management\", and \"Performance\". \"Corporate reporting\", \"Literature review\", \"Nutrition\", and other terms were instead classified as intermittent research topics.