The word "resilience" is now frequently invoked when describing 9/11 survivors. It's not just a catchphrase — the research bears out the fact that we seem to have certain innate coping skills to get us through disasters. Prospective and longitudinal studies of people who were impacted the most suggest that the proportion of survivors who developed chronic problems, such as PTSD or complicated grief, rarely exceeded 30 percent, and in some cases was considerably lower. Several surveys of rescue and recovery workers and other first responders estimated prevalence rates for PTSD between 6 and 12 percent; for World Trade Center evacuees it was 15 percent