Analyses of Physician Visits From Childhood and Adolescent Cancer Survivors

Suli Ma successfully defended her thesis entitled "Analyses of Physician Visits From Childhood and Adolescent Cancer Survivors" on 24 July 2009.

The main focus of the CAYACS program on health care service at BC Cancer Agency is the long-term effect of childhood and adolescent cancer diagnosis on the survivors in multiple domains. One of its research objectives is to assess long-term resource needs of cancer survivors by using longitudinally collected physician visit records from a survivor cohort. This thesis project conducts various analyses of the data to evaluate frequency and cost of the physician visits in two different time scales, calendar time and individual time. Missing costs associated with the visits are imputed based on a relevant variable. Starting with cross-sectional analyses, we obtain results comparable to those from the previous CAYACS project in physician visits. We investigate the frequency and cost of the whole cohort over (calendar) time with time series analyses. Some issues of possible general interest, such as the association between general practitioner visits and specialist visits of the cohort and seasonal pattern in the physician visits, are examined in this project. Furthermore, in an individual time scale base, we analyze the physician visits to provide both population-based and individual-based inferences on the effects of risk factors including time period of diagnosis, diagnosis type and other demographic factors with several longitudinal models. The Box-Cox transformation is applied and the method in Lin, et al (1999) is adapted to deal with the non-normally distributed physician visit costs with a positive mass on zero.

This type of interdisciplinary work is a hallmark of our program in Applied Statistics at Simon Fraser University. For more information, please contact Suli Ma ( or her supervisor Joan Hu (, Department of Statistics and Actuarial Science.