# Understanding How GitHub Supports
## 4 Results
### The Emerging Role of Curation Repositories
#### 4.2.3 Participation in Curation Repositories  
This subsection concerns about how GitHub collaborative features are used in curation repositories. For 40 out of 49 of the curation repositories, only the owners pushed changes to the main branch of the repository. In 48 of the curation repositories, multiple contributors made contributions through pull requests. The number of contributors a curation repository had is presented in Table 6. The majority of curation repositories had more than 10 contributors. Contributors of curation repositories appropriate the existing functions of GitHub to contribute to the repositories. In 29 curation repositories, there were contributors who made suggestions of resources in the issue tracker. Usually, they forked the curation repository to their own space, made a modification, and sent a pull request to the owner, which is the same process as the collaboration on software repositories on GitHub ([PERSON], 2014). For each curation repository, we examined all pull requests that were created before August 31, 2014 to extract the proportion of pull requests with more than two participants involved. At the time of this step of the analysis, one curation repository was no longer available because of copyright issues. One repository did not have any other contributors and thus did not have any issues or pull requests. In addition, we eliminated six curation repositories that had less than three pull requests from this analysis. Therefore, this analysis was performed on 42 repositories. The results in Table 7 show that the contributions made to the majority of curation projects happened between only two people (contributor and owner). Rarely were there cases in which a third person was involved in a pull request to evaluate the resource or to make a comment (Table 7). This may be effective for owners to manage the curation repositories, since after contributors suggest an item, they can evaluate and then make a decision without introducing further steps. However, such mechanism might affect the quality of the alleged high-quality resources, since only two persons examine a new item. \begin{table}
\begin{tabular}{c c c} \hline \hline
**\# of Contributors** & **\# Curation Repos** & **Percent** \\ \hline \(<\)10 & 13 & 26.5\% \\ Between 10 and 100 & 33 & 67.3\% \\ \(>\)100 & 3 & 6.2\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The number of contributors to curation repositories. \begin{table}
\begin{tabular}{c c c} \hline \hline
**\# Followers** & **\# Owners** & **Percent** \\ \hline \(<\)10 & 22 & 46.8\% \\ Between 10 and 100 & 15 & 31.9\% \\ \(\geq\)100 & 10 & 21.3\% \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The number of GitHub users following curation repository owners prior to the creation of curation projects. To further understand how curation repositories are changed by pull requests, we retrieved all pull requests that where created before August 31, 2014 for the 42 curation repositories and the line changes for each using the GitHub API. We defined the following three types of pull requests, using \"addition\" to denote the number of lines added in a pull request and \"deletion\" to denote the number of lines deleted in a pull request:  
\(\square\) _Type Add_: in this pull request,  
addition > 0 and deletion = 0, or  
addition > 0 and deletion > 0 and (addition - deletion) > deletion  
\(\square\) _Type Delete_: in this pull request:  
addition = 0 and deletion > 0, or  
addition > 0 and deletion > 0 and (deletion - addition) > addition  
\(\square\) _Type Update_: the remaining cases, where addition and deletion were similar. Following this definition of types of pull requests, for each curation repository, we calculated the percentage of each type of pull requests and plotted the results in Figure 3. The results showed that in most repositories of this sample, _Type Delete_ represented a very small portion of the pull requests (less than 10%), while _Type Add_ dominated most curation repositories, and _Type Update_ represented a limited proportion.