The executive vice president of Robotics, Inc., is concerned because the cost of materials has not been in line with the budget for several periods, even after implementing an EOQ model. The company implements the typical direct material variance computations for price and quantity at the end of each month. The price variance of the direct materials used is usually near expectations. The vice president does not understand how the budget differences are always larger than the material price variances. What explanation can you give for these issues?