1. A data processing apparatus comprising: a predicting unit configured to calculate a prediction value of time series data with respect to input of the time series data using a prediction model for predicting the time series data; a determining unit configured to determine a target value of the time series data using the prediction value of the time series data; an error calculating unit configured to calculate, via a processor, an error of the prediction value relative to the target value; and a retrieving unit configured to retrieve and input error reduction data as part of the time series data input into the prediction model to reduce the error of the prediction value.