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Abstract
This study has presented the concept and practices of enlarged JIT and determined its impact on JIT implementation and performance of the production system. Enlarged JIT has been defined as a set of activities which facilitate JIT production and thus improve the performance of the production system. Specifically, enlarged JIT will help reduce uncertainties in customers' demand and thus stabilize master production schedules. Stabilizing MPS has been frequently mentioned as a prerequisite in implementing JIT. Such activities would include establishing a direct communication link with customer plants, improving frequency of deliveries to customer plants, effective communication links in producer plants, and other supporting activities.
To determine the impact of enlarged JIT on production, several hypotheses were developed as to the relationships between enlarged JIT and both the implementation of other JIT practices and system performance. To test the proposed hypotheses, data were collected using questionnaires. Hotelling's T$\sp2$ test and discriminant analysis were used to test the two proposed hypotheses.
The result of statistical analysis shows that companies utilizing enlarged JIT are implementing JIT to a greater extent in all eight functional areas than companies not doing so. Even though the interrelationship of JIT implementation among those areas has not been specifically stated, one would anticipate that enlarged JIT helps stabilize part or all of the master production schedules in advance and provides uniform and level schedules by eliminating unnecessary demand fluctuations in the production system, which in turn facilitates JIT production in every other area.
The result also indicates that companies utilizing enlarged JIT achieve greater performance improvement in terms of cost, quality, flexibility, and delivery. There is a strong indication that the nine enlarged JIT practices are important facilitators of JIT implementation and thus contributors to higher performance improvement. Factor analysis shows that the essence of enlarged JIT consists of two factors: communication and reverse implementation of JIT purchasing.
