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Steps in Constructing an np-Chart

Steps in Constructing an np-Chart: The np Chart can be used for the special case when the subgroups are of equal size. Then it is not necessary to convert nonconforming counts into the proportions phat(i). Rather, one can directly plot the counts x(i) versus the subgroup number i.

Steps in Constructing a u-Chart

Steps in Constructing a u-Chart: The u Chart is used when it is not possible to have an inspection unit of a fixed size (e.g., 12 defects counted in one square foot), rather the number of nonconformities is per inspection unit where the inspection unit may not be exactly one square foot…it may be an intact panel or other object, different in sizethan exactly one square foot. When it is converted into a ratio per square foot, or some other measure, it may be controlled with a u chart. Notice that the number no longer has to be integer as with the c chart.

Steps in Constructing a c-Chart

Steps in Constructing a c-Chart: The c Chart measures the number of nonconformities per “unit” and is denoted by c. This “unit” is commonly referred to as an inspection unit and may be “per day” or “per square foot” of some other predetermined sensible rate.

Steps In Constructing An X-Bar and s Control Chart

Steps in Constructing an X-Bar and s Control Chart: This document contains the step-by-step instructions to construct an X-Bar and s control chart. First the s chart is constructed. If the s chart validates that the process variation is in statistical control, the XBAR chart is constructed.

Steps in Constructing an X-Bar and R Control Chart

Steps in Constructing an X-Bar and R Control Chart: This document contains the step-by-step instructions to construct an X-bar and R control chart. First the R chart is constructed. If the R chart validates that the process variation is in statistical control, the XBAR chart is constructed.

Steps in Constructing a Median And Range Control Chart

Steps in Constructing a Median And Range Control Chart: This document contains the step-by-step instructions to construct a Median And Range control chart. The primary reason for using medians is that it is easier to do on the shop floor because no arithmetic must be done. The person doing the charting can simply order the data and pick the center element.

Yield to Sigma Conversion Table

When you know your process yield (percentage of a process that is free of defects), you can use this yield to sigma conversion table to easily determine your process sigma level, as well as your process defects per million opportunities.