Tonic immobility predicts poorer recovery from posttraumatic stress disorder.

Background: Tonic immobility (TI; a state of motor arrest during threat) and has been found to be associated with the development of psychopathology. It also hindered recovery from posttraumatic stress disorder (PTSD) after pharmacological treatment. The present study investigated the role of TI in recovery from PTSD in a large representative community sample with mixed traumas outside an exclusive treatment context.

The latent class multitrait-multimethod model.

A latent class multitrait-multimethod (MTMM) model is proposed to estimate random and systematic measurement error in categorical survey questions while making fewer assumptions than have been made so far in such evaluations, allowing for possible extreme response behavior and other nonmonotone effects. The method is a combination of the MTMM research design of Campbell and Fiske (1959), the basic response model for survey questions of Saris and Andrews (1991), and the latent class factor model of Vermunt and Magidson (2004, pp. 227-230).