# On the Relationship between Self-Admitted Technical Debt Removals and Technical Debt Measures
## 4 Results
#### 4.1.2 Change in TD Value between Commit Removal and Subsequent Commit  
Differently from the previous case, this analysis considers the commit of the SATD removal and its consecutive. For each system analyzed, Table 4 shows, in the first column, the type of delta trend between the commit removal and the consecutive commit, and in next columns, the number of files found for each projects.  
Table 4 shows that for Log4j in 46.03% of cases (29 files), the file has been removed, while in 42.86% of cases (27 files), the TD remains unchanged between subsequent commits. For 7.94% of cases (5 files), there was an increase in the value of the metric under examination, while for the remaining 3.17% (2 files), a decrease in value was found. Specifically, the increase in TD changes in a range from 0.6 to 8%, while the decrease is between 25% and 50%.  
In Gerrit, as in the previous case, there is a high percentage of cases 45.07% (32 files) where the file has been removed. The table points out that in 47.89% of cases (34 files), the TD value remains unchanged in subsequent commits. Instead, for 4.23% of cases (3 files), there is an increase in the value of TD, while just 2.82% (2 files) correspond to a decrease in value. In the commits analyzed, we observed the intensity of increase ranging from 5 to 48%, instead of the decrease from 7 to 40%.  
In Hadoop, there is the highest percentage of files not found, 69.27% (142 files); in 26.34% of cases (54 files), the TD value remains unchanged in subsequent commits. For 1.95% of the cases (5 files), an increase in the value of the TD was found. Tomcat is the only system in which the percentage of the increase varies in a much wider range, more in detail, between 0.27% and 160%, with a case in which it even reaches 800% because it varies from 3 min to 27 min. Instead, for 2.44% (4 files), a decrease in the value was found, with a percentage of change that varies between 3% and 9%.  
As for Gerrit also in the case of Tomcat, the highest percentages refer to the number of cases for which the files are not found, 49.36% (235 files), and there were no changes in the value of the TD between the commit analyzed and its subsequent, 46.63% (222 files).  
For 1.7% (8 files), there is an increase in the TD value with a percentage of change that varies between 0.23% and 21%, while for 2.31% (11 files), there is an improvement in the TD value, which is recorded as a decrease in the value itself. This decrease in the value varies between 0.81% and 67%.  
Overall, these results confirm the ones obtained in the previous analysis and show that the impact on the TD values is the maintained in subcommits. Then, if the removal of SATD leads to a change in the TD values, this can be observed even in the subsequent commits.  
Figure 3 highlights that the highest percentages concern cases of files not found, followed by unchanged, unlike the previous analysis, where the highest percentage was recorded in the decrease in the TD value. These results suggest that in most cases, developers tend not to reevaluate their modification choices once they have intervened on a certain class, leaving the code for subsequent commits unchanged or modifying it marginally.  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & & & \multicolumn{3}{c}{**Number of Files**} \\ \hline
**Delta** & **Log4j** & **Gerrit** & **Hadoop** & **Tomcat** & **Delta** \\ \hline File not found & 29 & 32 & 142 & 235 & File not found \\ \hline Unchanged & 27 & 34 & 54 & 222 & Unchanged \\ \hline Increased & 5 & 3 & 5 & 8 & Increased \\ \hline \hline \end{tabular}
\end{table}
Table 4: Removal commit analysis vs. consecutive commit.