In continuous review inventory model, (${varrho}$, ${gamma}$) system, order quantity(${varrho}$) and reorder point(${gamma}$) should be determined to calculate inventory-related cost that consists of setup, holding, and penalty costs. The procedure to obtain the exact value of ${varrho}$ and ${gamma}$ is complex. In this paper, a regression analysis is proposed to get the approximate inventory-related cost without the determination of ${varrho}$ and ${gamma}$ in the case that the standard deviation(${sigma}$) of the lead time demand is small or that the mean(${mu}$) of the lead time demand is proportional to ${sigma}$. To save inventory-related cost, central warehouses with (${varrho}$, ${gamma}$) system can be built. Central warehouse can provide some stores with products with the consideration of the tradeoff between inventory-related cost and transportation cost. The number and the location of central warehouses to cover all the stores are determined by a regression-based approach. The performance of the proposed approach is tested by using some computational experiments.