L. de Boer

Practice and promise of formal supplier selection: a study of four empirical cases

In this paper an experimental study of formal decision-making models for supplier selection is described. Attention is paid to all phases of the supplier selection process: the recognition of the need for a new supplier, the formulation of decision criteria, the qualification of suitable candidates and final selection. It appears from the experiments that formal decision models may prove to be useful in various ways throughout the whole supplier selection process and in different purchasing situations.

A basis for modelling the costs of supplier selection: the economic tender quantity

In this paper, we consider the decision a purchaser must make regarding the number of suppliers that should be invited to submit a tender for a certain purchase. On the one hand, the costs of sending invitations to tender, the costs of evaluating the tenders received, and the costs of communicating the outcome to the suppliers that were not selected, all increase with the number of suppliers that are invited to tender. On the other hand, with every additional tender, the purchaser might obtain a better bid. We present a theoretical decision model, the Economic Tender Quantity (ETQ) model, that under certain conditions may assist the purchaser in finding the number of tenderers that minimises the expected total costs of the tender process, that is the sum of the expected costs of sending, evaluating and communicating, and the expected bid price. We discuss these conditions and possible extensions, as well as future research opportunities in this area.

Design of a Load Cell for the Wagner Distractor

A leg length inequality can be treated by using a Wagner distractor. With this apparatus, it is possible to extend the upper or lower leg slowly. By analysing the measurements of the axial force acting on the femur or tibia the treatment can be optimized and soft tissue damage prevented. To measure the axial force, a load cell has been designed and constructed. This load cell is built into a Wagner distractor and connected with a specially designed measuring amplifier. The load cell and amplifier do not interfere with the lengthening procedure. They are safe for the patient and have an acceptable error of 7 per cent.