“…The variation is in how nondaily smoking is defi ned: specifi cally, whether a defi nition is descriptive but imprecise ( " nondaily, " " some-day use, " " occasional, " " occasional but not regularly " ); whether a minimum is specifi ed for lifetime consumption (e.g., at least 100 cigarettes or 100 times); or whether the defi nition is based on cigarettes smoked per day, average number of cigarettes smoked per day, or days or times smoked in a week or a month ( Biener & Albers, 2004 ;Borland, 1994 ;DiFranza et al, 2000 ;Etter, 2004 ;Etter, Le Houezec, & Perneger, 2003 ;Evans et al, 1992 ;Fergusson & Horwood, 1995 ;Fornai et al, 2001 ;Gilpin et al, 1997 ;Hennrikus, Jeffery, & Lando, 1996 ;Hines, Fretz, & Nollen, 1998 ;Hines, Nollen, & Fretz, 1996 ;Holmen, Barrett-Connor, Holmen, & Bjermer, 2000 ;Kenford et al, 2005 ;Koontz et al, 2004 ;Luoto, Uutela, & Puska, 2000 ;McDermott, Dobson, & Owen, 2007 ;Morley et al, 2006 ;Okuyemi et al, 2004 ;Okuyemi, Richter, et al, 2002 ;Paavola, Vartiainen, & Puska, 2001 ;Sargent, Mott, & Stevens, 1998 ;Stanton et al, 2007 ;Stone & Kristeller, 1992 ;Wetter et al, 2004 ;Zhu et al, 2003 ).…”