When monitoring variability in statistical process control, conventional Shewhart R and S charts are used where the in-control readings have a constant variance. These charts cannot be used, however, in certain instances when the coefficient of variation, rather than the variance, must be constant. A chart is proposed that is similar to the S chart and uses rational groups of observations for monitoring the coefficient of variation.
© 2001-2024 Fundación Dialnet · Todos los derechos reservados