Mann told Antonio Regalado of the Wall Street Journal that he would not be “intimidated” into releasing source code for MBH98. Here is an account of correspondence with Mann and with the U.S. National Science Foundation: Even before publication of MM03, we politely requested clarification on issues in MBH98. This was a source of controversy […]
I have sometimes been asked why I don’t start a FOI action with respect to source code and source data from the various multiproxy authors. I don’t preclude the possibility totally. However, my first inclination has been to attempt first to obtain the data and code from the authors through a direct and polite request, […]
In some recent commentary trying to backpedal from the hockey stick, "detection and attribution" studies have been cited as alternative validations and Hegerl et al [2003] is cited as a key example. I have not looked in detail at these studies, but some features of Hegerl at al. [2003] struck me as so obvious that […]
This next replication exercises shows the results of attempting to reconstruct the NH temperature index from the archived RPCs, with the usual puzzling discrepancies.
Mann et al. have archived 3 slightly varying versions of the their "dense" subset and one version of their "sparse" subset. The dense series extend later than the temperature dataset archived at the Corrigendum SI and said to the the source for MBH98 instrumental data. The sparse subset can be reconstructed resaonably closely (but not […]
I notice that the phrase "spaghetti diagram" is catching on a little. In connection with MM05, we archived 100 simulated PC1s, using the weird method of MB98. Just for fun, here’s a spaghetti diagram from 6 of these, chosen from the 100 at random, with 25-year smooths. You’ll see why I’m pretty unimpressed with spaghetti […]
If you go to the original Nature Supplementary Information for MBH98 here, and try to inspect the list of data and list of verification stats (such as they are), you will find that they are no longer there. Update: here
This is an interesting and amusing comment on factor analysis, a technique very closely related to principal component analysis: J. Scott Armstrong, Derivation of Theory by Means of Factor Analysis or Tom Swift and His Electric Factor Analysis Machine, The American Statistician, 1967, 17-21 Link
This is the first replication note that gets into the meat of our emulation. Previously we’ve noted the non-replicability of certain MBH98 steps, but, since relevant intermediate calculations were archived, we were able to proceed using the archived intermediate calculations. Here we show the key replication step calculating “reconstructed [temperature] principal component” series. Archiving is […]
Khim et al. [2002] reported that a core from the Eastern Bramsfield Basin, Antarctic Peninsula showed that the LIA and MWP were the strongest of the Late Holocene cold and warm periods.
Climate Audit 
Mann on Source Code
Mann told Antonio Regalado of the Wall Street Journal that he would not be “intimidated” into releasing source code for MBH98. Here is an account of correspondence with Mann and with the U.S. National Science Foundation: Even before publication of MM03, we politely requested clarification on issues in MBH98. This was a source of controversy […]