Experimental Setup The baseline method we consider is the one in (<cite>Barzilay and McKeown, 2001</cite> ) without sentence alignment -as the bug reports are usually of one sentence long. We call <cite>it</cite> BL. As described in Sec. 2, <cite>BL</cite> utilizes a threshold to control the number of patterns mined. In the experiment, we find that running <cite>BL</cite> using <cite>their</cite> default threshold of 0.95 on the 5,935 parallel bug reports only gives us 18 paraphrases. This number is too small for practical purposes. Therefore, we reduce the threshold to get more paraphrases.