Capability Analysis (Between/Within)overview data how to example see also
Capability Analysis (Between/Within)Stat > Quality Tools > Capability Analysis > Between/Within
Use Capability Analysis (Between/Within) to produce a process capability report using both between-subgroup and within-subgroup variation. When you collect data in subgroups, random error within subgroups may not be the only source of variation to consider. There may also be random error between subgroups. Under these conditions, the between/within process variation is due to both the between-subgroup variation and the within-subgroup variation.
Capability Analysis (Between/Within) computes standard deviations within-subgroups and between-subgroups, or you may specify historical standard deviations. These will be combined (pooled) to compute the between/within standard deviation. The between/within standard deviation will be used to calculate the capability statistics, such as Cp and Cpk.
The report includes a capability histogram overlaid with two normal curves, and a complete table of overall and between/within capability statistics. The normal curves are generated using the process mean and overall standard deviation and the process mean and between/within standard deviation.
The report also includes statistics of the process data, such as the process mean, target, if you enter one, between/within and overall standard deviation, and observed and expected performance.
Data are arranged as
Single column: Choose if data is in one column. Enter a column.
Subgroup size (use a constant or an ID column): Enter the subgroup size (for equal-size subgroups) or a column of subscripts (for unequal-size subgroups).
Subgroups across rows of: Choose if subgroups are arranged in rows across several columns. Enter the columns
Lower spec: Enter the lower specification limit. Choose Boundary to define the number as a "hard" limit. See Upper spec below for an explanation.
Upper spec: Enter the upper specification limit. Choose Boundary to define the number as a "hard" limit, meaning that it is impossible for a measurement to fall outside the limit.
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Note |
You must enter at least an upper or lower spec. When you define upper and lower specification limits as boundaries, Minitab sets the expected percentage of values that are out of specifications to * for a boundary. |
Historical mean (optional): Enter a value for the mean of the population distribution if you have a known process parameter or an estimate obtained from past data. If you do not specify a value for the mean, it is estimated from the data.
Historical standard deviations:
Within subgroup: (optional): Enter a value for the within-subgroup standard deviation of the population distribution if you have a known process parameter or an estimate obtained from past data. If you do not specify a value for sigma, it is estimated from the data. Minitab can estimate within-subgroup sigma in one of three ways.
Between subgroups: (optional): Enter a value for the between-subgroup standard deviation of the population distribution if you have a known process parameter or an estimate obtained from past data. If you do not specify a value for sigma, it is estimated from the data. Minitab can estimate between-subgroup sigma in one of three ways