Most often, prospective studies are conducted over short periods, with few following study participants for longer than a decade (Giovannucci et al., 1994; Howard et al., 1998; Ostbye, Taylor, & Jung, 2002; Weir, 1970; Yuan et al., 1996), and many measuring smoking behavior during only one assessment (Engeland, Haldorsen, Anderson, & Tretli, 1996; Enstrom, 1999; Hirdes, Brown, Vigoda, Forbes, & Crawford, 1987; Lam et al., 1997; Rogot & Murray, 1989). Among studies of United States populations with the longest periods of repeated longitudinal smoking assessment, including the Framingham Study (Freund, Belanger, D’Agostino, & Kannel, 1993; Freund, 1992; Gordon, 1975) and the First Cancer Prevention Study (CPS-I) (Knoke, Shanks, Vaugh, Thun, & Burns, 2004; Thun, Day-Lally, Calle, Flanders, & Heath Jr, 1995; Thun & Heath Jr, 1997), baseline smoking behavior is captured at entry through reports by adults who have long passed the age of risk for smoking initiation and established use. Because most smokers quit and relapse repeatedly before abstaining permanently, short term, compressed, and averaged smoking measurements are necessarily simplifications of the quitting process (USDHHS, 1990), and fail to maximally characterize changes in smoking behavior across the lifespan.
