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R = x max - x min. The normal distribution is the basis for the charts and requires the following assumptions: The quality characteristic to be monitored is adequately modeled by a normally distributed random variable; The parameters μ and σ for the random variable are the same for each unit and each unit is independent of its predecessors or ...
The X-bar chart is always used in conjunction with a variation chart such as the ¯ and R chart or ¯ and s chart. The R-chart shows sample ranges (difference between the largest and the smallest values in the sample), while the s-chart shows the samples' standard deviation. The R-chart was preferred in times when calculations were performed ...
Distribution-free control chart; DOE mean plot; ... Fan chart (statistics) Fan chart (time series) ... X̅ and R chart; X̅ and s chart; X-bar chart
As with the ¯ and R and individuals control charts, the ¯ chart is only valid if the within-sample variability is constant. [5] Thus, the s chart is examined before the x ¯ {\displaystyle {\bar {x}}} chart; if the s chart indicates the sample variability is in statistical control, then the x ¯ {\displaystyle {\bar {x}}} chart is examined to ...
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To this plot is added a line at the average value, x and lines at the UCL and LCL values. On a separate graph, the calculated ranges MR i are plotted. A line is added for the average value, MR and second line is plotted for the range upper control limit (UCL r).
X bar, x̄ (or X̄) or X-bar may refer to: X-bar theory, a component of linguistic theory; Arithmetic mean, a commonly used type of average; An X-bar, a rollover protection structure; Roman numeral 10,000 in vinculum form
The Western Electric rules are decision rules in statistical process control for detecting out-of-control or non-random conditions on control charts. [1] Locations of the observations relative to the control chart control limits (typically at ±3 standard deviations) and centerline indicate whether the process in question should be investigated for assignable causes.