Abstract
Maintenance activities and otehr indirect works are one of te major areas of cost saving and contorl available to indusries today. Comparative Estimating is one of te techniques of setting up the time standard for indirect works and in such system, UMS is developed for the measure of maintenance work. These methods are suitable for a long cycle, non-repetitive type of work. But they don't make clear the precision of standard time estimation. We define the precision and compare 3 kinds of comparative estimating for the quick change of the condition. If we use such technique, it is convenient for maintenance and audit of the standard time data.
