Time Series Analysis of Monthly Suicide Rates in West of Iran, 2006–2013

Abstract

Introduction: Iran’s western provinces have higher suicide rate compared to the other provinces of the country. Although suicide rates fluctuate over time, suitable statistical models can describe their underlying stochastic dynamics.

Methods: This study was conducted to explore the fluctuations of the monthly suicide rates in the most populated western province of Iran using exponential
smoothing state space model to compute the forecasts. For this reason, the monthly frequencies of completed suicides were converted to rates per 100,000 and a state‑space approach was identifed and ftted to the monthly suicide rates. Diagnostic checks were performed to determine the adequacy of the ftted model.

Results: A signifcant seasonal variation was detected in completed suicide with
a peak in August. Diagnostic checks and the time series graph of the observed monthly suicide rates against predicted values from the ftted model showed that in the study period (from March 2006 to September 2013), the observed and predicted values were in agreement. Thus, the model was used to obtain the short‑term forecasts of the monthly suicide rates.

Conclusions: In this study, we had no signifcant trend but seasonal variations in the suicide rates that were identifed. However, additional data from other parts of the country with longer duration are needed to visualize the reliable trend of suicide and identify seasonality of suicide across the country.

Keywords: Exponential smoothing state space model, forecast, suicide, time series