Or that there is a better model than an AR1.

Unless AR1 describes global temperature perfectly, then certainly there must be a better model. Haven’t a clue what it is, though.

]]>With a Markov process, you don’t care about the path by which you got to x3: x4 will be the same no matter what the different possible x2, x1, etc.

That’s a good description. I spent a lot of time with Markov this past semester in a Stochastic Modeling class and our teacher was nice enough to make sure we understood this very point.

Mark

]]>Hmm. Bit spacey … ]]>

What you say is true, but there are lots of different combinations of x0, e0, e1 and e2 which could get you to any given x3. With a Markov process, you don’t care about the path by which you got to x3: x4 will be the same no matter what the different possible x2, x1, etc.

Demetris’ point is basically that a climate system must have some “momentum”. You could imagine a point 50 years before the depths of the Little Ice Age, and a point 50 years after, where a snapshot of the global mean temperature would be the same at both points. But it would not be reasonable to say that the environment one year after each of those points has the same probability distribution.

]]>BTW, #14 Do you mean the Cooley&Tukey Tukey?

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