Nicotine withdrawal symptoms have been characterized using more than two dozen research based methods (4–5). Withdrawal symptoms characterize smokers’ levels of irritability, restlessness, insomnia, depression, concentration, appetite, and cravings and urges for tobacco over many differing time periods ranging from weeks (6) to years (7–8). Nicotine withdrawal symptoms are highly correlated and methods have been used to summarize these symptoms, including the use of latent class analyses (9–10) and Rasch models (11). A unidimensional Rasch model of nicotine withdrawal sensitivity was constructed in a sample of 1,644 smokers reporting quitting for 3 months or more at least once (11). The Rasch modeled nicotine withdrawal sensitivity score enables analysis of multiple highly correlated nicotine withdrawal symptoms in a single analysis, and is significantly associated with an increased hazard ratio with respect to the duration of these attempts, as well as to smoking intensity, and a shorter time to first cigarette in the morning (11). Rasch models have also been previously used to evaluate the unidimensionality and associations of established measures of nicotine dependence (12), and of additional measures of nicotine dependence and their relationship to items within established measures of nicotine dependence (13).
