Int. J. Environ. Res. Public Health 2009, 6 2. Material & Methods 2.1. Analysis of the Social Differentiation of Smoking, 2000-2008 610 In order to investigate the social differentiation of cigarette smoking in France, we first used data abstracted from several telephone surveys conducted by the National Institute for Prevention and Health Education (INPES) between 2000 and 2008. These surveys have been carried out with a very similar methodology, among representative samples of French aged 18-75 in 2000 (sample size N=13,685), 2003 (N=3,085), 2005 (N=30,513), 2006 (N=3,206), 2007 (N=6,007) and 2008 (N=2,000) [16]. For each survey, a weighting procedure was computed to improve the sampling: distributions in each sample were adjusted to distributions in the French population for age, gender, occupation, geographic area and size of town (thanks to data available from the 1999 and 2005 French Census). We used these data to compare the trends in smoking prevalence for three contrasted occupational categories: executive managers and professional occupations, manual workers, and unemployed people. We computed standard z-tests to compare the proportions of smokers across time (for a given occupational category) and across occupational status (for a given year). The trends in smoking prevalence were also compared with the evolution of the standard price of cigarette packs. 2.2. Quantitative Analysis of Smoking Motives: Poor Smokers versus Other Smokers We focused on the last telephone surveyed conducted by the INPES in 2008 among a random sample of 2,000 respondents aged 18-75 because this survey, contrary to previous ones, included questions dealing with smoking motives and smokers‟ reactions to the cigarette price increase. Within each selected household, the „next birthday‟ method was used to choose which member of the household should be asked to participate to the survey (i.e. the investigator asked which person had his birthday closest in the future). If this person was absent or could not respond at once, the investigator proposed a later appointment. In case of refusal, he/she was not replaced by another member of his/her household. The response rate reached 71%. Among the 2,000 respondents, 621 were smokers (for further methodological details on INPES telephone surveys, see [17]). Respondents were asked about the current financial situation of their household with the following response items: “wealthy”, “satisfying”, “it‟s a bit on the short side”, “It‟s hard to make both ends meet‟, “we had to get into debt”. We considered that those smokers who answered “It‟s hard to make both ends meet” or “we had to get into debt” were poor smokers, while other items corresponded to “other smokers”. In order to check the consistency of this categorisation, we first detailed the corresponding sociodemographic profiles: household income level, respondent‟s educational level and occupational status, being a single parent, as well as gender and age. Then we compared poor smokers and other smokers‟ according to their smoking habits (daily consumption of cigarettes, tobacco dependency with the short Fagerström test [18]), their reactions to the cigarette price increase (smoking cheaper or hand-rolled cigarettes, reducing one‟s cigarette consumption), and their smoking motives (adapted from [19]: the original scale – a 23-item questionnaire – was too long for our study): automatic smoking, aid to socialisation, enjoyment, stress relief, improvement in concentration, to take one‟s mind off cares and worries, weight control (respondents were asked to rate each motive on a