ABSTRACS This research is aimed at finding out the method used by PT. Tri Jaya Plastik Utama Surakarta in arranging its selling forecast. It is also aimed at finding out the most suitable forecasting technique applied by PT. Tri Jaya Plastik Utama Surakarta in arranging its selling budget. Related to the problems, this research is conducted by using half-average trend method, moment trend method, least square trend method, and quadratic trend method. The arrangement of selling forecast in this research was done by using selling volume data from 2000 until 2006. The comparison of results between the trend previously arranged and the reality is used to calculate Forecasting Error Standard. The values of Forecasting Error Standard is used to determine the most appropriate method to be applied in arranging the company’s selling budget. The smallest Forecasting Error Standard Value will show that the arranged forecast is close to the reality. The result of the analyses shows that the company has arranged the selling budget by kualitative method, that is opinion from manager and their staffs which have direct selling related, and the result of Forecasting Error Standard by using half-average method are 816,85 for Big Top, 859,71 for Economy 225, and 870,96 for Modern; by using the moment method, the results are 252,03 for Big Top, 264,72 for Economy 225, 268,5 for Modern; by using least square method the results are 251,8 for Big Top, 264,55 for Economy 225, 268,5 for Modern; by quadratic method the results are 147,98 for Big Top, 83,6 for Economy 225 and 23,18 for Modern. From the evidence above, it can be concluded that quadratic trend method has the smallest Forecasting Error Standard.Based on the findings above, it is suggested that PT. Tri Jaya Plastik Utama Surakarta arrange its selling budget by using quadratic trend method due to its smallest Forecasting Error Standard. The company can also compare between the 2007 selling budget arranged by the researcher and the reality in the future.
