Undoubtedly, many will find the defining and classification of the business cycle to be semantics - figuring that economic activity "is what it is." However, I believe that the correct interpretation of the business cycle is imperative in understanding future implications and correctly setting expectations.
Of course, the "official" entity for defining and classifying economic periods into "business cycles" is the NBER Business Cycle Dating Committee (BCDC). While I don't agree with many aspects of the BCDC's methodologies and conclusions, I do find their work interesting.
Among other things, I find it notable (as documented in the "The NBER's Business Cycle Dating Procedure: Frequently Asked Questions") that the BCDC does not define or classify a (economic) Depression. This is something I wrote of in the November 30, 2011 post titled "Defining An Economic Depression." As well, another aspect I find notable is that the concept of a "Double Dip Recession" is not defined or classified.
While I don't necessarily agree (my thoughts on the issue are complex and can best be summarized in "A Special Note On Our Economic Situation") with the BCDC's classification of the June 2009-current period as an economic "expansion," if one assumes such is the case, various interesting comparisons can be made relative to past "expansionary" periods.
One characteristic that seems to lack widespread recognition is how long one might reasonably expect this current (putative) "expansion" to continue, given the BCDC-defined history of such previous expansions. While I certainly don't believe that the duration of an expansion is of paramount importance in defining its potential future longevity, at the same time I believe that duration should be considered.
Given the BCDC-defined June 2009 end of the recession, the current "expansion" is, of course, now over four years old. If one reviews the statistics concerning business cycles, seen on the BCDC's "U.S. Business Cycle Expansions and Contractions" page, one sees various statistics concerning the duration of past business cycles. While there are various methods (and periods) in which the past business cycles are summarized, one sees that the current post-June 2009 "expansion" is "getting up there" relative to the average duration of "expansions" as measured by the "Previous trough to this peak" measurement. However, if one only looks at the post-1990 "expansions," one can see that these three "expansionary" periods (ending in June 2009) have been "lengthy" compared to the average of various previous periods.
The Special Note summarizes my overall thoughts about our economic situation
SPX at 1690.91 as this post is written