SPC and Global Warming: 1880 – 2021

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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 (4)

  • Mike MercerJanuary 27, 2022 Reply

    Using Wayne Taylors Change Point Analysis program, he picks up the same last three periods, each off only by a year from yours. (https://variation.com/product/change-point-analyzer/)

  • Scott HindleFebruary 1, 2022 Reply

    Dear Bill

    Thanks as always for a thought provoking article.

    Figure 5 left me wondering. With three sets of limits, and stability within each set, you effectively say that the process or system changes occurs at the moment of the detected shifts / step changes, i.e. 2001-2 and 2014-15.

    Shewhart spoke of a predominant cause accounting for a control chart signal. Is it realistic to suggest that a dominant cause takes effect so suddenly, and in between things are largely unchanged? Your Figure 4 trend control chart looks to me to contain no signal of change; wouldn’t a more continuous change over time more accurately reflect what is going on?

    If Figure 5 was from a production process we’d be focusing (investigating) on the points in time where you identify the step changes, and tell people that in the other periods things were stable so little mileage in these periods. For global temperatures I struggle to think that changes occur so rapidly and then we go to unchanging periods of several years … What do you think of this?

    Thanks, Scott.

    • billFebruary 1, 2022 Reply

      HI Scott,
      Thanks for the reply.  Yes, I agree with  your comments and others have pointed that to me as well.  It is difficult for me to imagine what would cause a step change like that all the sudden, but I don't see too many trends that seem to plateau so often before it moves again.  I don't have a good answer on what would cause that to occur.  The last two plateaus have been 13 and 15 years and the current one is at 7 years.  Just don't see that in other trends.

  • Ângela Lopes PintoFebruary 8, 2022 Reply

    Well done! Great analysis! 

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