## 4 Empirical Evaluation
### Results Analysis  
(1) (RQ1): Investigation of the systematicity of the review abstracts  
Table 3 shows the distribution of the confidence values that each review abstract yielded. All the confidence values, therefore, vary between 5 and 80 (80 excluded). Sixty-two of the review abstracts yield a confidence varying between 40 and 60 (60 excluded): these, therefore, have a Medium level confidence. Fifty-nine of the review abstracts yield a confidence varying between 20 and 40 (40 excluded): these therefore have a Low-level confidence. Only seven review abstracts have a confidence varying between 60 and 80 (80 excluded): they therefore have a Medium High confidence. None of the review abstracts has a confidence that is at least 80% (i.e., High). This allows us to conclude that all the analyzed review abstracts exhibit a suboptimal systematicity and hence, a suboptimal adherence to Check-SE 2022. \begin{table}
\begin{tabular}{c c c} \hline \hline _OConfidence_ Range (Interval) & _OConfidence_ Interpretation & **Number of Reviews in the Range** \\ \hline \hline [0, 1[ & Invalid & 0 \\ \hline \hline [1, 5[ & Extremely Low & 0 \\ \hline \hline [5, 20[ & Very Low & 23 \\ \hline [20, 40[ & Low & 59 \\ \hline [40, 60[ & Medium & 62 \\ \hline [60, 80[ & Medium High & 7 \\ \hline [80, 95[ & High & 0 \\ \hline [95, 99[ & Very High & 0 \\ \hline [99, 99, 9[ & Extremely High & 0 \\ \hline [99, 9, 100[ & Valid & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Confidence of the Review Abstracts. (RQ2): Influence of the Publication Year on the Systematicity of the Reviews' Abstracts  
Figure 1 shows the variations of the _OConfidence_ values that the analyzed review abstracts yield. It, therefore, indicates that the confidence of these reviews varies from one year to another, with highest variations scored in years 2016 and 2017. (3) (RQ3): Influence of the Well-Established Prisma Reporting Guideline on the Systematicity of the Review Abstracts  
Figure 2 shows the variations of the _OConfidence_ values that the analyzed PRISMA review abstracts yield. Based on Figure 2, we can conclude that the PRISMA-driven review abstracts, therefore, yield relatively higher _OConfidence_ values than all the analyzed review abstracts (see Figure 1). Based on the timeline that Figure 2 reports, we can also conclude that the software engineering community has recently started to use the well-established PRISMA reporting guideline, the least recent analyzed PRISMA-driven review dating back 2019. (4) (RQ4): Minimal set of items that review abstracts usually report  
Figure 3 shows a summary of the answers of the eleven questions that we extracted from the analyzed review abstracts. That Figure allows us to conclude that questions 1, 2, 7,  
Figure 1: Variation of the _OConfidence_ throughout the years. Figure 2: Variation of the _OConfidence_ throughout the years for the PRISMA-driven reviews. and 10 are those that most of the analyzed abstracts have appropriately answered. Hence, when writing the review abstracts, most of systematic reviewers ensured that:  
* The abstract identifies the review as systematic (question 1)
* The abstract stated the main objective(s) or question(s) that the review addressed (question 2)
* The abstract specified the total number of included studies and participants and summarize relevant characteristics of studies (question 7)
* The abstract provided a general interpretation of the results as well as important implications (question 10). As stated in Section III.B, [PERSON] et al. [26] recommended reporting at least items 2, 4, 6, 8, and 10 of the PRISMA 2020 for abstracts checklist as they are the most critical. But Figure 3 shows that existing reviews do not comply with that requirement, as they mostly focused on answering questions 1, 2, 7, and 10 that correspond to items 1, 2, 7, and 10 in the PRISMA 2020 for abstracts checklist.