Here is a metastudy that will show that complexity, coupling and size were found to be strongly related to fault proneness. https://arxiv.org/abs/1601.01447 ht

Here is a metastudy that will show that complexity, coupling and size were found to be strongly related to fault proneness. https://arxiv.org/abs/1601.01447 https://arxiv.org/abs/1601.01447 There is lots of studies that show that modularity is one of the most significant factors for evaluating maintainability of OO systems.