Maximizing follow-up in longitudinal studies of traumatized populations.

Although longitudinal research is essential in understanding the nature and course of posttraumatic mental health problems, high rates of attrition often threaten the internal validity of such studies and make results hard to interpret. C. K. Scott (2004) developed an approach to minimizing attrition in longitudinal studies that consistently yielded retention rates in excess of 90% through to 2-year follow-up. In this article, the authors discuss the interface between trauma exposure and participation in longitudinal research, before describing in detail a model to address those effects. The effectiveness of the model is examined with reference to traumatic stress in a large community sample (N = 887) with eight waves of data over 2 years.