A Times Series Analysis Of Monthly Sales Of Petrol In A P'etroleum Filling Station: A Case Study Of Conoil Plc, 25 Aba Road, Umuahia, Abia State

ABSTRACT

Time series approach was used to study sales data in a filling station. The data were collected from a Conoil Petrol Station in Umuahia. The distribution of Autocorrelation and Partial Autocorrelation functions suggested a Seasonal Autoregressive Integrated Moving Average Model, given by SARIMA (1, 1, 1) X (1, 0, 0)12. The parameters of the SARIIMA were estimated with statistical software MTNITAB). The following mathematical model was obtained: Yt= °°565Yt..i + °•7207Yt...12 — ° 0407Yt-13 + et - 1.0097 et_i From the above model, estimates and two years forecast were obtained. The correlogram of the residual explains a pure white noise process for the error of the model.