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Question 38

If a process has subgroups for Variable data and the process runs for a long period of time, then the best pair of SPC Charts to use would be an Xbar and

_________.

    Correct Answer: C

    When dealing with variable data and subgroups in a long-running process, the best pair of SPC charts to use are the Xbar Chart and R Chart. The Xbar Chart monitors the process mean over time using the averages of subgroups, while the R Chart monitors the range, or dispersion, within those subgroups. Other options like NP Chart, Individuals Chart, and C Chart are not suitable because NP and C charts are used for attribute data, while the Individuals Chart is used for data that comes in single, individual measurements rather than in subgroups.

Discussion
InvisibleBeingOption: C

A. NP Chart is for attribute data and not for variable data. B. Individual Chart is used for variable data but only when you have just 1 subgroup. D. C Chart is used for attribute data and not for variable data. C. R chart is the only option in the list that can be used with variable data and when you have more than 1 subgroup. If you read carefully, the question says "If a process has subgroups".