Aggregate production planning is the process of determining (1) the timing and quantity of production, (2) the level of inventories, (3) the number of workers employed, and (4) the amount of overtime used for up to 12 months ahead. Production and inventories are stated in overall or aggregate quantities, such as number of automobiles without regard to model or color or number of pairs of shoes without regard to style or size. Cost minimization is rarely the only goal in aggregate planning. Other considerations, such as stability of the workforce and maintenance of adequate inventory levels, are usually just as important.