American Statistical Association
New York City
Metropolitan Area Chapter

Memorial Sloan-Kettering Cancer Center
Biostatistics Seminar

Yuelin Li, Ph.D.
Assistant Attending Behavioral Scientist
Memorial Sloan-Kettering Cancer Center


The prospective relationship between cancer risk perceptions and behavior change is bidirectional; perceived risk increases health protective behavior and health protective behavior decreases perceived risk (Brewer, et al., 2004; Hay et al., 2007). Use of binary HLM to capture this reciprocal determinism is not ideal since perceived risk and behavior change are confounded across repeated assessments. The use of a classic economic model may be useful in conceptualizing the dynamic interplay of these two variables. We developed a dynamic Smoking Cessation Equilibrium model based on Alfred Marshalls standard Supply and Demand framework (1920). The model was fitted to data assessed from newly diagnosed patients (N=188) with tobacco-related malignancies, most of whom were hospitalized for surgical resection. Patients cancer risk perceptions, measured on a scale (ranging from 1= Not Likely, 5=Extremely Likely) and smoking status (7-day point prevalence) were assessed at baseline, and at three and 12 months subsequently. Individuals with higher cancer-related risk perceptions at baseline and three months subsequently abstained from smoking by twelve months (slope = 0.13 logits); those who abstain at baseline and 3 months subsequently lowered their perceived risk (slope = - 0.42 logits). The equilibrium point is at a perceived risk of 2.56 (3 = moderately likely to get cancer if I continue smoking), with an 85% chance of sustained abstinence, and represents the point at the highest probability of abstinence and lowest probability of relapse. An intervention designed to increase risk perceptions to a new equilibrium of 3.0 would result in 3% of these individuals relapsing to smoking. Modeling this dynamic equilibrium in smoking cessation may shed light on the optimal point at which cancer risk communication interventions may maximize behavior change uptake as well as maintenance over time, and may thus be useful in testing theoretical approaches that focus on maintenance of behavior change.

Date: Wednesday, April 25, 2007
Time: 4:00 P.M. - 5:00 P.M.
Location: Memorial Sloan-Kettering Cancer Center
Department of Epidemiology and Biostatistics
307 East 63rd Street
(between First and Second Avenues)
3rd Floor Conference Room
New York, New York
Note: To gain access to the building, please follow the directions by the telephone in the foyer.


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