Here is a list of all previous price drops of 15 percent or more. Peak, trough, number of days from peak to tough, and percent price drop.
1 2010-07-19 0.09 2010-07-24 0.05 5 44.4
2 2010-11-07 0.36 2010-12-10 0.19 33 47.2
3 2011-01-16 0.39 2011-01-19 0.31 3 20.5
4 2011-02-14 1.06 2011-04-05 0.67 50 36.8
5 2011-05-14 7.86 2011-05-21 5.97 7 24.0
6 2011-06-09 29.58 2011-11-18 2.14 156 92.8
7 2012-01-08 7.05 2012-02-16 4.19 39 40.6
8 2012-08-17 13.26 2012-08-19 9.09 2 31.4
9 2013-04-09 214.67 2013-04-16 65.33 7 69.6
The longest crash lasted 156 days. It has now been 153 days since the April 9 peak.
Typically, though, crashes are over very quickly. The median is only 7 days. The mean is 33.6 days.
Great research.
The big difference between 2011 and 2013 is that the parabolic rise took 3 months now instead of 2 months in 2011. Hence why I think the correction will also take longer. If like 2011 the correction would be also 2.5 longer than the parabolic rise that would be 225 days or 7.5 months after April 9th peak = end November.