National long-term care insurance started in July, 2008. We try to make up for weak points and develop a long-term care insurance system. Especially, it is important to upgrade the rating model of the category of need for long-term care continually. We improve the rating model using the data after enforcement of the system to reflect the rapidly changing long-term care marketplace. A decision tree model was adpoted to upgrade the rating model that makes it easy to compare with the current

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... . This model is based on the first assumption that, a person with worse functional conditions needs more long-term care services than others. Second, the volume of long-term care services are defined as a service time. This study was conducted to reflect the changing circumstances. Rating models have to be continually improved to reflect changing circumstances, like the infrastructure of the system or the characteristics of the insurance beneficiary.