Asian Journal of Mathematics & Statistics1994-54182077-2068Asian Network for Scientific Information10.3923/ajms.2008.63.68EkpenyongEmmanuel John 1200811This study improves on the Additive
Fourier Series and traditional model of discrete periodic time series.
It seeks to formulate a mixed (multiplicative-additive) Fourier Series
model which decomposes a time series into multiplicative trend, seasonal
components and additive error component together with additive trend.
It is discovered that for time series with strongly marked and obviously
fluctuating seasonal effects a multiplicative-additive (mixed) Fourier
series model is suitable. The relevance of the new model is shown by analyzing
the rainfall data of Uyo metropolis with the use of the model. The resulting
model gives Y_{t} = 210.1 (1-0.984 cos ωt) which fits well
to the original data and can be used in forecasting future values of the
rainfall data.]]>Anonymous,2001Chatfield, C.,1975Findley, D.F., B.C. Mansell, W.R. Bell, M.C. Otto and B.C. Chen,1998Hernmann, H., T. Liebig and K. Todter,2006Nkpodot, U.T.C. and A.E. Usoro,2005Priestley, M.B.,1981Roerink,2000