Commenting in StackOverflow

In StackOverflow, both questions and replies can receive comments from users. In StackOverflow environment, users can comment on both questions and replies. There are a total of 29,222,308 comments¹². 41% of them are made on questions while the rest of them are on replies. An example question and reply with comments is presented in Figure 5.7. Comments consist of comment content, author information and timestamp of the posting time. Similar to question and replies, users can also vote for comments as seen next to the comments. The votes received do not affect the relative ranking of comments, rather they are ordered by their posting time. This is mainly due to protect the conversational structure within comment threads. For example, in Figure 5.7, user MeqDotNet asked a question with posting a comment, and user Usman Y replied MeqDotNet’s question again with commenting.

Our initial goal was to understand why users leave comments in the first place. Therefore, we manually analyzed a set of comments and grouped them into categories. Even though these categories may not cover all cases of comments, they still give some underlying understanding of comments in general.

Comments on questions can be divided mainly into two categories. The first group of comments on questions is constructed to clarify a point in question, make it more understandable and unambiguous in general. The askers can use these comments to make their question more clear. An example of this user case is provided in Figure 5.8. The left side of the figure displays the original initial posted question (Figure 5.8(a)) and edits made to the question¹³(Figures 5.8(c) and 5.8(e)). The right side of the figure shows the comments on question which led to those changes (Figures 5.8(b), 5.8(d) and 5.8(f)). As seen in the figure, after a question is posted, users use comments to ask for clarifications or make suggestions. Depending on these comments, askers may make changes to the original question. In this example, two suggestions were made by users, and asker used both of these suggestions and made the necessary edits in the question.

The second group of comments on questions is to provide answers to the question. An example to this is given in Figure 5.9. In the example, the first comment provides a correct reply

12There are another 4036 comments without any parents (either question or reply). These questions or replies are probably deleted from the system, but comments made on them are still available.

13Text in green shows the edits.

Figure 5.7: An example question and reply with comments.

to the question. The first reply which is accepted as best by the asker also refers to the same comment as a correct reply. The reason why users prefer to post the answer as comment rather than as reply is unknown. One possible reason can be that user is a newly joined user who is hesitant to answer the question; however, it is not the case in this example. User ”Dieter” is among the top 3% most reputed users in StackOverflow with more than 600 posted replies at the time he posted this comment.

Another example to this case is available in Figure 5.7. In this example, all question comments are providing a reply to the question. The first two comments (by users Jordan and Eduardo) and the first reply which was accepted as the best reply by asker and received the highest number of votes from other users were all posted at the same time. The two comments are almost the same and very brief, while the reply is more explanatory and detailed. These brief comments with replies observed in this example and also within the example in Figure 5.9 suggest that maybe users tend to leave comments when they are in hurry, or not available to give an elaborate reply.

The comments on replies can be also categorized into two groups. The first group of com-ments praises the answer and while the second group of comcom-ments suggests corrections or

(a) Initial question. (b) Comment made to the question.

(c) Edited question (First edit). (d) Comments made to the question.

(e) Edited question (Second edit). (f) Comments made to the question.

Figure 5.8: An example question and comments made on it in order to clarify the question.

improvements to the reply. Example to both of these cases are presented in Figure 5.10 and continued in Figure 5.11. Similar to Figure 5.8, the left side of the figure presents the original and edited replies, while the right side of the figure show the comments. Figure 5.10(a) displays the question and the initial reply. Figure 5.10(b) contains two comments; the first comment (from Oliver) can be categorized into the first category while the second comment (from Steve) is an example to second category. Steve made a suggestion which had been considered by Nawaz (the author of reply) and necessary edits were performed in Figure 5.10(c). In Figures 5.10(d), 5.11(b) and 5.11(d) we see other users making suggestions to the reply, and Figures 5.11(a) and 5.11(c) show how the author of the reply respond to these suggestions.

In Figures 5.8 and 5.11 we also see the author of question or reply communicating with commenters through comments. Getting into dialog with other commenters is yet another common case of commenting which can be observed in both questions and replies. In these situations, users may resolve an issue through back and forth commenting to each other.

Figure 5.9: An example question and a comment which contains the answer.