(Click here if you need control charts for attributes) This wizard computes the Lower and Upper Control Limits (LCL, UCL) and the Center Line (CL) for monitoring the process mean and variability of continuous measurement data using Shewhart X-bar, R-chart and S-chart.
- Process mean: Estimate the process mean by averaging over the set of samples, or enter the target mean (μ) if you have that value.
- Process standard deviation (σ): If you don't have a known value for the standard deviation (e.g. from historic data), compute S by averaging the standard deviations of the samples, or R by averaging across the ranges of the samples. The range of a sample is the difference between the maximum and minimum observations. In general, S is a more accurate method.