# The Trends and Content of Research Related to the Sustainable Development Goals: A Systemic Review
## 3 Results and Discussions
### Work of the Hierarchical Agglomerative Clustering Technique
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Cluster No.** & **Number of Citations** & **Name of the Cluster** \\ \hline
389 & [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] A systematic study of sustainable development goal (SDG) interactions. _Earth's Future_ 2017, 5, 1169-1179. [91] & Synergies and trade-offs \\  & 108 & [PERSON], [PERSON], and [PERSON] Sustainable Development Goals (SDGs): Are we successful in turning trade-offs into synergies? _Palgrave Commun._ 2019, _5, 1-11. [92] & Critical issues, inequality, and education \\ \hline
2 & 63 & [PERSON] The victims of unsustainability: A challenge to sustainable development goals. _Int. J. Sustain. Dev. World Ecol._ 2016, _23, 113-121. [93] & Critical issues, inequality, and education \\ \hline
3 & 65 & [PERSON], [PERSON], [PERSON], and [PERSON] Multi-criteria model for sustainable development using goal programming applied to the United Arab Emirates. _Energy Policy_ 2015, _87_, 447-454. [95] & Systems analysis \\  & 34 & [PERSON], [PERSON], [PERSON], and [PERSON] [PERSON] A Weighted Goal Programming model for planning sustainable development applied to Gulf Cooperation Council Countries. _Appl. Energy_ 2017, _185_, 1931-1939. [96] & Systems analysis \\ \hline
4 & 33 & [PERSON] [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] Interactions among Sustainable Development Goals: Knowledge for identifying multipliers and virtuous cycles. _Statistic. Dev._ 2020, _28_, 1236-1250. [97] & Interaction, comparison, and classification \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The 11 clusters derived by CATAR and the corresponding numbers and percentages of papers and the characteristic terms. The information obtained so far can be demonstrated using the Multidimensional Scaling (MDS) technique of CATAR. The relative positions between any two clusters were calculated for depicting the theme map. A circle represents a cluster of articles, and the area reflects the number of papers included. The distances between two circles signify their strength of connectivity. A shorter length means they are closely interrelated. The theme map derived by CATAR is shown in Figure 4. We invited several experts in the areas of sustainability science, environmental education, and CSR to read the exporting documents of CATAR and attempt to derive concise and integrated group names that can embrace most of the central ideas and methodologies of the closely related clusters. It was evident that the eight clusters could be merged into three more prominent clusters. Cluster 1 was unique as one conceptual category with much more papers than others. Clusters 2, 6, and 8 were closely interrelated to each other. Clusters 3, 4, 5, and 7 formed another group. The groups were named \"synergies and trade-offs\", \"networking\", and \"systems analysis\", as described below. Group 1: synergies and trade-offs  
Group 2: networking (to combat critical inequity in basic needs such as water and education)  
Group 3: systems analysis (of interactions between stakeholders for resilient transformation)  
The information shown in Figure 4 indicates that synergies and trade-offs between various issues and SDGs have been the focus during these years. As this group contained only one big cluster, we expect more relevant studies to be published shortly. Group 2 (networking) consists of three clusters related to critical reflection regarding how SDGs may exert negative impacts on people's basic needs in low-income societies. The three clusters overlapped each other, especially cluster 2 and cluster 8, showing water issues highly connected to inequality. This echoed the statement that \"water is a basic human right\", argued by the UN and in many reports and studies [84,106]. Group 3 also contains four closely covered clusters, in which cluster 3 and cluster 4 share the most common areas. The studies included were traditional sustainability-oriented studies on interaction, comparison, and classification of complicated systems using mathematical and economic tools.