"In the end, we learned two things. Periods without stock-market crashes are very safe, in the sense that depressions are extremely unlikely. However, periods experiencing stock-market crashes, such as 2008-09 in the U.S., represent a serious threat. The odds are roughly one-in-five that the current recession will snowball into the macroeconomic decline of 10% or more that is the hallmark of a depression.
The bright side of a 20% depression probability is the 80% chance of avoiding a depression. The U.S. had stock-market crashes in 2000-02 (by 42%) and 1973-74 (49%) and, in each case, experienced only mild recessions. Hence, if we are lucky, the current downturn will also be moderate, though likely worse than the other U.S. post-World War II recessions, including 1982."