“How to” with Minitab

What is a U Chart? The U chart is a type of control chart used to monitor discrete (count) data where the sample size is greater than one, typically the average number of defects per unit. Defect vs. Defective Remember the difference between defect and defective? A defect of a unit is the unit’s characteristic…

What is an IR Chart? The IR chart (also called individual-moving range chart or I-MR chart) is a popular control chart for continuous data with subgroup size equal to one. [unordered_list style=”star”] The I chart plots an individual observation as a data point. The MR chart plots the absolute value of the difference between two…

Xbar R Chart The Xbar R chart is a control chart for continuous data with a constant subgroup size between two and ten. [unordered_list style=”star”] The Xbar chart plots the average of a subgroup as a data point. The R chart plots the difference between the highest and lowest values within a subgroup as a…

What is a Xbar S Chart? The X-S chart (also called Xbar S chart) is a control chart for continuous data with a constant subgroup size greater than ten. The Xbar chart plots the average of a subgroup as a data point. The S chart plots the standard deviation within a subgroup as a data…

What is a NP Chart? The NP chart is a control chart monitoring the count of defectives. It plots the number of defectives in one subgroup as a data point. The subgroup size of the NP-chart is constant. The underlying distribution of this control chart is binomial distribution. NP Chart Equations NP-chart Data Point: Center…

What is a CumSum Chart? The CumSum chart (also called cumulative sum control chart or CUSUM chart) is a control chart of monitoring the cumulative sum of the subgroup mean deviations from the process target. It detects the shift of the process mean from the process target over time. The underlying distribution of the CuSum…

What is an EWMA Chart? The EWMA chart (Exponentially-Weighted Moving Average Chart) is a control chart monitoring the exponentially-weighted average of previous and present subgroup means. The more recent data get more weight than older data. It detects the shift of the process mean from the process target over time. The underlying distribution of the…