Int. J. Environ. Res. Public Health 2009, 6 2. Methods 2.1. The Hospital and Staff 2814 The hospital in our study was located in a rural area in eastern Taiwan which had emerged from an asylum established in 1965. The asylum was a governmental institution aimed to take long-term care of homeless or chronic psychiatric patients. In the early days there were only a few medical doctors and nurses to take care of the patients’ psychiatric and medical problems. The administration of the asylum was under a veteran’s hospital which was operated more as a military facility than a hospital. In the 1990s, partly due to the pressures from human rights groups, the asylum became independent from the veteran’s hospital and was reestablished as a modern psychiatric hospital. Currently, it has more than 2,700 psychiatric in-patients, about 85% of them with diagnoses of schizophrenia. The average admission of patients over 65 years of age in the hospital was about 16 years [23]. According to their mental status they were arranged to live in different settings, including two acute wards, seven chronic wards and four rehabilitation centers. There were about 200 psychiatric nurses and nurse aides employed during data collection for this study. The main task of the nursing aides in this hospital is helping nurses with medical care, instructing and supervising patients in daily life activities, and keeping the environment clean, and they are in direct contact with patients, just all the same as nurses are [24]. 2.2. Study Procedure This study followed the Helsinki Declarations. Before it began we had sent out a protocol describing the purposes, methods of data collection, uses of data, and guarantees for the privacy of participants to the institutional bioethics committee charged with permitting this research and we got their approval. Then we set up a reporting system on the website where the cohort members could report violent events after they had obtained their account and password. After we were certain that the reporting system was working well, we recruited a total of 174 nurse and nursing staff volunteers into this study; the participant rate was about 87%. The reasons of non-participation included that they were too busy; they did not know the study; they could not use the computer. All of participants signed an informed consent and practiced the procedure until they could access the website smoothly and complete the report correctly. On the website, we first put a basic questionnaire which included demographics, working history, and the anxiety level using a question as “how you fear the threat of workplace violence caused by patients?”. This question was taken from a questionnaire developed by ILO/ICN/WHO/PSI1 that has been translated into Chinese and validated for content validity and test- retest reliability (0.85) and then back translated into English for verification of the accuracy of translation. The degree of anxiety was divided into the following five categories: not at all, a little bit, moderate, quite a bit and extreme [24]. Before the formal follow-up period started they all were asked to finish it. After that in the follow-up period, if they were attacked by patients or colleagues in the working environment and felt hurt, they should use the Internet to complete three report forms: the Event Form, the Victim Form, and the Perpetrator Form. The Event Form contains 12 questions asking about the type of violence, its severity, date, time, the situation, etc. The Victim Form contains 17