When a control run was not obtained, and on analysis, it is hard to tell if a response is present, there is a technique that can be used.  Take the initial wave and subtract the replication run wave.  This difference waveform (shown in black) is similar to a control run.  These runs are from a different case.  Notice that the left ear runs replicate fairly well and each is of low amplitude. The subtraction run, which shows how much the two runs differ from each other, is small.  In the left ear, the size of the wave V peak is larger than the subtraction wave, giving more confidence in marking the small wave V.  However, for the right ear runs, the traces do not replicate terribly well, as shown by the larger amplitude of the subtraction run.  Obtaining a third trace at 30 for the right ear would be a good idea.  I would not have a lot of confidence in the right ear response being present.  The audiologist uses the subtraction run concept in case 13.