title: Review the number of accidents in Tehran over a two-year period and prediction of the number of events based on a time-series model.
abstract: BACKGROUND
  One of the significant dangers that threaten people's lives is the increased risk of accidents. Annually, more than 1.3 million people die around the world as a result of accidents, and it has been estimated that approximately 300 deaths occur daily due to traffic accidents in the world with more than 50% of that number being people who were not even passengers in the cars. The aim of this study was to examine traffic accidents in Tehran and forecast the number of future accidents using a time-series model.
  
  
  METHODS
  The study was a cross-sectional study that was conducted in 2011. The sample population was all traffic accidents that caused death and physical injuries in Tehran in 2010 and 2011, as registered in the Tehran Emergency ward. The present study used Minitab 15 software to provide a description of accidents in Tehran for the specified time period as well as those that occurred during April 2012.
  
  
  RESULTS
  The results indicated that the average number of daily traffic accidents in Tehran in 2010 was 187 with a standard deviation of 83.6. In 2011, there was an average of 180 daily traffic accidents with a standard deviation of 39.5. One-way analysis of variance indicated that the average number of accidents in the city was different for different months of the year (P < 0.05). Most of the accidents occurred in March, July, August, and September. Thus, more accidents occurred in the summer than in the other seasons. The number of accidents was predicted based on an auto-regressive, moving average (ARMA) for April 2012. The number of accidents displayed a seasonal trend. The prediction of the number of accidents in the city during April of 2012 indicated that a total of 4,459 accidents would occur with mean of 149 accidents per day during these three months.
  
  
  CONCLUSIONS
  The number of accidents in Tehran displayed a seasonal trend, and the number of accidents was different for different seasons of the year.
authors.affiliation: M.Sc. Student of Occupational Health, Department of Occupational Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Ghulam Heidar
authors.initials: GH
authors.lastname: Teymuri
authors.affiliation: M.Sc. of Occupational Health, Department of Occupational Health, Ahvaz University of Medical Sciences, Ahvaz, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Sadeghian
authors.affiliation: M.Sc. Student of Occupational Health, Department of Occupational Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Kangavari
authors.affiliation: Ph.D. Student of Occupational Health, Department of Occupational Health, Arak University of Medical Sciences, Arak, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Asghari
authors.affiliation: M.Sc. of Biostatistics, Department of Occupational Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Elham
authors.initials: E
authors.lastname: Madrese
authors.affiliation: M.Sc. Student of Occupational Health, Department of Occupational Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Abbasinia
authors.affiliation: MD of Industrial Medicine of Oil Company, Iranian petroleum industry health research institute, Tehran, Iran.
authors.forename: Iman
authors.initials: I
authors.lastname: Ahmadnezhad
authors.affiliation: B.Sc. of Occupational Health, Department of Occupational Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Yavar
authors.initials: Y
authors.lastname: Gholizadeh
keywords: Accidents; Forecasting; Humans