Logistic Regression Using SAS®: Theory and Application

8.2. Longitudinal Example

Let’s begin with an example of longitudinal (panel) data. The sample consisted of 316 people who survived residential fires in the Philadelphia area (Keane et al. 1996). They were interviewed at 3 months, 6 months, and 12 months after the fire. The outcome variable PTSD is coded 1 if the person had symptoms of post-traumatic stress disorder and 0 otherwise. The explanatory variables measured at each interview are

CONTROL	A scale of a person’s perceived control over several areas of life.
PROBLEMS	The total number of problems reported in several areas of life.
SEVENT	The number of stressful events reported since the last interview.

In addition, there is one variable that was measured only at the initial interview:

COHES