Abstract
Large variance between estimated and actual cost is a big problem to small and medium-sized BTO manufacturers. Since they produce one-off products, they estimate the cost of production according to design drawings and specification sheets every time they receive orders. Many of them have neither estimation standard nor unified costing method. Thus, the estimation is dependent on individual skills. We think that is the main reason of the variance. We investigated the estimation of a certain small manufacturer and found the mean, variance, maximum and minimum of the estimation error rate were, 29.7%, 109.1, 1820%, -36.6% respectively and confirmed the large variance. We plan to investigate the variance in detail and improve estimation accuracy.
