To help put aside some of the Great Depression comparisons I created this chart to compare price deflations - peak to trough(present). You can see the 3.5 yrs of price deflation - beginning Nov 1929 when the CPI peaked - that coincided with the start of the G.D. in the blue lines(dark blue = CPI; light blue = PPI for commodities). The dotted red line is the current CPI Index beginning in July of 2008 (the high point) and dotted pink is the current Commodity PPI. It's clear how massive inflationary stimuli arrested the precipitous decline, which began in fall '08 with a far more significant drop in commodity prices than during the G.D.(the PPI comm index peaked prior to Nov '29 but for a clean comparison I used that date). Also, one should ask the obvious question: how does the current under-statement -if indeed there is any - of the official inflation #'s affect the relationship of the indexes in the chart?
