Data come from the 18 WMH surveys that used an expanded assessment of PTSD (described below) to examine PTSD associated with randomly selected traumatic experiences (Table 1). These surveys included 10 in countries classified by The World Bank (2012) as high-income countries [national surveys in Belgium, France, Germany, Italy, The Netherlands, Northern Ireland, Spain, United States, along with regional surveys in Japan (a number of metropolitan areas) and Spain (Murcia)] and eight in countries classified as low-/middle-income countries (national surveys in Lebanon, Peru, Romania, South Africa, and Ukraine along with surveys of all non-rural areas in Colombia and Mexico and a separate regional survey in Medellin, Colombia). Each survey was based on a probability sample of household residents in the target population using a multi-stage clustered area probability design. Response rates had weighted averages of 84.7% in low-/lower-middle-income countries, 79.8% in upper-middle-income countries, 63.5% in high-income countries, and 70.3% overall. Four surveys had response rates below the minimally acceptable level of 60% (45.9% in France, 50.6% in Belgium, 55.1% in Japan, 56.4% in The Netherlands). A detailed description of sampling procedures is presented elsewhere (Heeringa et al. 2008).
