  Pull request latency evaluation is an essential application of effort
evaluation in the pull-based development scenario. It can help the reviewers
sort the pull request queue, remind developers about the review processing
time, speed up the review process and accelerate software development. There is
a lack of work that systematically organizes the factors that affect pull
request latency. Also, there is no related work discussing the differences and
variations in characteristics in different scenarios and contexts. In this
paper, we collected relevant factors through a literature review approach. Then
we assessed their relative importance in five scenarios and six different
contexts using the mixed-effects linear regression model. We find that the
relative importance of factors differs in different scenarios, e.g., the first
response time of the reviewer is most important when there exist comments.
Meanwhile, the number of commits in a pull request has a more significant
impact on pull request latency when closing than submitting due to changes in
contributions brought about by the review process.
