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.