Dimensionality and reliability of the Civilian Mississippi Scale for PTSD in a postearthquake community

This study examines psychometric properties of the Civilian Mississippi Sca le for posttraumatic stress disorder when administered in a community surve y of 656 persons following the 1989 Loma Prieta earthquake. Internal consis tency was lower (Cronbach's alpha = .73) than for previous analyses of civi lian and combat versions of the Mississippi Scale. The analysis produced on e strong factor composed of 25 items with regular wording and a second weak er factor composed of 10 items with reversed wording. Internal consistency was higher when the 10 reversed items were removed (Cronbach's alpha = .86) ; the two factors were negatively correlated Traumatic experiences and psyc hological distress measures explained more variance in the 25-item factor t han in the 35-item scale. Further studies should focus on content analysis and performance of the reversed items.