Question for skeptics: Is this an appropriate use of the derivative operation?

Damn it jim, I am a jim and an engineer. It didn't work for me either but I doubt it matters. I would say that they have to clearly state what they are doing. I have no problems with models if they clearly list their limitations and assumptions. What happens is the results of those models and simulations often get those limitations filtered out and are given to the public and politicians as fact when in fact the assumptions are poorly understood and probably wrong. We are all waiting with baited breath to hear from the guardians of science, Dana et al.

The link doesn't work (at least for me).

There are multiple methods used to reduce noise and decern a signal especially from time series data. I'm not familiar with the research you linked to (nor can I access it), but dendrochronolgy studies typically go through two detrendings, the first being an exponential decay function to remove age related decline in tree growth and the second can be anything from a linear fit to a moving average to remove "stand dynamics" variation. However a dendrochronolgist in my lab is perfectly willing to admit that there is as much art to this process as there is science.

Edit: I'm still waiting for one of the all-knowing to enlighten the rest of us.

when comparing change and rates of change, derivatives is the only way to do it, in this case it's not a textbook mathematical derivative. This was simply a difference operation dSO=a*(SO(i)-SO(i+1))-c, performed on a data series. The author was simply trying to see the lag between the SO data set and certain UAH data sets.

Just off hand, a script of 200 to 300 lines of code could have handled the data nicely. Whay does this have to do with sceptics and AGW?, the paper does not address AGW.

Damn it Jim, I'm an engineer not a number cruncher.

I'm not sure the point of this question but I'm going to guess that if I can't come up with the correct answer then I'll fail the test an need to hand in my skeptic membership card. I must say, you guys are really grasping at straws lately.

Edit: The link doesn't work because there is punctuation at the end of it. Just remove that period and parantheis.

Note for all, when you put in http links, make sure there is no punctuation around it. It must stand on it's own.

"derivative values based on variations" can mean a lot of things none of which are necessarily good or bad. There is nothing wrong with mollifying curves to smooth graphs. This can be revealing. Using "derivatives" of surrounding values may or may not be more judicious.

The question is whether the data have been kept pristine. Why THESE tree rings and not THOSE? How is outlying data handled? Where is data truncated...?

Looking at the Yamal data, in which 1200 trees where available...you're saying that Briffa's removal of 1197 of the trees was just "removing the noise"?

Sometimes yes, but you must clearly state what you are doing and what your assumptions are. You will also need to IMHO, compare your results with the noise included, if the error is too large then you have falty data and need to run the test again.

Is the link correct? I'm not able to open it.

It is pathetic and telling when alarmists have to search for something that isn't criminal or unethical.