What? My Data are Not Normal?

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Thanks so much for reading our publication. We hope you find it informative and useful. Happy charting and may the data always support your position.


Dr. Bill McNeese
BPI Consulting, LLC

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Comments (3)

  • Shishpal SinghJune 30, 2016 Reply

    Respected SirThanks for sharing the important article on data to see the normal distribution and tools associated with that.Best RegardsShishpal Singh

  • Wayne G. Fischer, PhDJuly 3, 2016 Reply

    Nice article…but:First you write, “There are a variety of tools to help you determine if the data are normally distributed or not. The three key ones (in my opinion) are: Control charts…”. Then you write, “Please note that being in statistical control does not mean that your data are normally distributed. A control chart does not tell you that.”RE Figure 1, I’d also recommend running the Individuals control chart without the two data points that appear to lie “outside” the rest of the data – they may be inflating the estiamted standard deviation and lie outside the re-calculated control limits. Control limits should be calculated using only data that vary due to Common Causes.

    • billJuly 3, 2016 Reply

      Thanks Wayne.  Yes, the control chart doesn't tell you if the data are normally distributed or not – just if the data came from a stable system to help you make a judement about the data itself.  So, I edited that sentence.  On Figure 1: the points appear to be part of the system based on the control limits, but yes, you could drop them out to see the impact on the data.

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