According to Allen, the company's assembly errors have been reduced by 43% since implementing SPC. (Chase, 1997)
             Benefits obtained can quickly repay any investment to implement SPC. The cost largely depends on the method used to collect and process the information. SPC systems generally fall into three main types: manual, semi-automated, and fully-automated.
             In a manual SPC system, a person records a small set of readings at regular intervals on a standard SPC form, along with the time and their name. A quick look at the chart for any trends is usually enough to check for potential problems. Advantages are that a manual system is flexible and requires no special equipment. Disadvantages are that it is less reliable than automated systems, more time consuming, and requires operator training.
             In a semi-automated SPC system, information is entered directly into a computer, either by typing or by a gauge linked to the computer. T
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