Forecasting incidence of intestinal infectious diseases in mainland China with ARIMA model and GM(1,1) model

Objective To forecast the incidence of three types of notifiable intestinal infectious diseases in mainland China with integrated autoregressive moving average model(ARIMA model) and grey model GM(1,1) respectively,and to assess the predictability of these models. Methods The ARIMA model was developed based on the monthly incidence of these diseases from January 1995 to December 2005.GM(1,1) model was developed based on the yearly incidence from 1995 to 2005.Both models were tested by the data in 2006.Relative error was used to validate the predictability of these models.The model with the least relative error was adopted to predict the yearly incidence in 2007 and 2008. Results The preferable model to forecast the yearly incidence of hepatitis A,diarrhea and typhoid fever was GM(1,1),ARIMA and GM(1,1) model respectively.Their corresponding relative error was 0.05%,5.47% and 38.89%.The estimated yearly incidence in 2007 for hepatitis A,diarrhea and typhoid fever was 4.59/105,30.84/105 and 2.53/105 respectively.In 2008,it was 4.03/105,29.03/105 and 2.34/105. Conclusions Several models should be estimated to forecast incidence of a certain intestinal infectious disease,and the best fitted model would be chosen for forecasting.