The essence of just-in-time: embedding diagnostic tests in work-systems to achieve operational excellence

This paper asserts that problem identification and problem-solving processes can be integrated into work processes by embedding tests in work that evaluate performance with every exchange of products, services, and information. These tests make it unambiguous when, where, and by whom problem solving is necessary. This hastens improvement and deepens process knowledge frequently and at low-cost. These assertions are based on an ethnographic study of how some firms sustain outstanding performance through iterative problem solving, a concern of organizational and operations management theory. This field research revealed attributes of just-in-time (JIT) as it is practiced by Toyota and its affiliates-companies that have been associated with JIT and that have been recognized for outstanding performance-that have not been fully explored previously. Whereas JIT's role in controlling material flows through sequential processes has been much discussed, Toyota and its affiliates also use JIT to evaluate work-system performance with high frequency and resolution. When work is not proceeding as designed, problem solving begins close in time, place, process and person to each problem. These results suggest using JIT to advance process knowledge from lower stages to higher.