Measure 3.1 concerned the number of cigarettes smoked per day when last smoked every day, based on the question ��When you last smoked every day, on average how many cigarettes selleck bio did you smoke each day?�� Measure 3.2 involved the total number of years smoked every day as determined by the item: ��Altogether, about how many years did you smoke every day? Do not include any time you stayed off cigarettes for 6 months or longer.�� Measure 4: Prior smoking status for ��never��-smokers. This measure is based on the survey question ��Have you EVER smoked at least 100 cigarettes in your entire life?�� We determined the frequency of respondents who were consistent in that they in 2003 reported being never-smokers (a response of ��No��) and had also reported having been a never-smoker in 2002.

In addition to the 100-cigarette item, the subsequent question, ��Do you now smoke cigarettes every day, some days, or not at all?�� determined current smoking (every day and some day choices) and former smoking (not at all choice). Analysis For continuous measures (Measures 1�C3), we first assessed summary statistics concerning the difference between 2002 and 2003 responses. This difference was defined as the 2003 value minus the 2002 value (and corrected by 365 days for Measure 1). Due to a possible rounding error, produced when data recorded in days, months, and years were converted into years for Measure 1 (the time since completely quitting smoking), an exact match was defined as an absolute value of the difference in responses of no more than 6 months.

For Measures 2 (age when first smoked fairly regularly) and 3 (the number of cigarettes smoked per day and the total number of years smoked every day), a match was assigned when the answers to 2002 and 2003 surveys were identical. For Measure 4 (prior smoking status among those reporting never smoked at a later time), a match was assigned for those reporting never smoking in both 2002 and 2003 and not a match for those reporting never smoking in 2003 who had reported any other smoking status in 2002. The odds ratios (ORs) of strict agreement between 2002 and 2003 responses were examined through multiple logistic regressions, which is commonly used in addition to descriptive reliability measures (Belli, Traugott, Young, & McGonagle, 1999; Cowling, Johnson, & Holbrook, 2003; Gillum, 2005; Huerta et al.

, 2005; Johnson & Mott, 2001). Factors of interest included age, sex, race/ethnicity, region, and metropolitan status, recorded in 2002. In addition, 2002 and 2003 interview methods were considered. Significance of all two-way Carfilzomib interactions and three-way interactions of survey methods in 2002 and 2003 and other variables were explored, while controlling for all main effects mentioned above. Analysis was done using SAS and SUDAAN (Research Triangle Institute, 2008).