In the current decade, software systems have been more intensively employed in every aspect of our lives. However, it is disappointing that the quality of software is far from satisfactory. More importantly, the complexity and size of today's software systems are increasing dramatically, which means that the number of required modifications is also increasing exponentially. Therefore, it is necessary to understand how function-level modifications impact the distribution of software bugs. In

more »

... tion, other factors such as a function's structural characteristics as well as attributes of functions themselves may also serve as informative indicators for software fault prediction. In this paper, we perform statistical methods and logistic regression to analyze the possible factors that are related to the distribution of software bugs. We demonstrate our study from the following five perspectives: 1) the distribution of bugs in time and space; 2) the distribution of function-level modifications in time and space; 3) the relationship between function-level modifications and functions' fault-proneness; 4) the relationship between functional attributes and functions' fault-proneness; and 5) the relationship between software structural characteristics and functions' fault-proneness. INDEX TERMS Bug, bug distribution, defected software systems, modifications, open source projects. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ VOLUME 8, 2020