Purchase lot sizing is done using a variety of techniques, and over one-quarter of the managers reported using multiple lot sizing techniques. The most common purchasing lot sizing techniques are dynamic lot sizing rules where historical consumption patterns, price breaks, and service level requirements may be taken into account. Lot-for-lot purchasing is also common because of the simplicity and the perception of holding lower amounts of inventory. Finally, one-fifth of firms routinely use fixed purchase lot sizing; the reason most cited being a vendor’s minimum purchase requirement. Purchase lot sizing provides a level of protection against variability in material recovery rates since orders are commonly planned to cover multiple periods. Managers cited a number of concerns with purchasing, the most common ones were: (1) long lead times (90%), (2) sole suppliers for a part or component (75%), (3) poor visibility of requirements (65%), and (4) small purchase orders and, as a result, unresponsive vendors (55%). Purchase lead times reported were highly variable; the mean time to receive an order ranged from 0.5 to 90 weeks. The variation in lead times is also very high, with coefficients of variation as high as 3.0 not uncommon. Purchased parts also cause a high percentage (~45%) of late orders