As far as the technological factors are concerned, it is often difficult to trace a quality problem back to a single cause. The failure of an instrument assembly into pass a final preshipment inspection may be caused by earlier acceptance of faulty purchased materials, improper machining or processing of certain components, faulty assembly Jigs, or any of a dozen other possibilities.
When these technological conditions have been traced, it is equally difficult to pin down the human factors. The faulty machining of a part may be due to carelessness of the machine operator, incorrect instruction by the foreman, to defective methods set up by the job planner, or a poor design by the engineer Curtly blaming a foreman, operator, or engineer on a superficial basis may are little bearing on the true problem .