Donald S. Kenkel, Maximilian D. Schmeiser, Carly J. Urban, May 2014. This paper estimates the causal income elasticity of smoking participation, cessation, and cigarette demand conditional upon participation. Using an instrumental variables (IV) estimation strategy finds that smoking appears to be a normal good among low-income adults: higher instrumented income is associated with an increase in the number of cigarettes consumed and a decrease in smoking cessation.

http://www.nber.org/papers/w20097