Category Archives: Replication

The Dot.Com Hockey Stick

I find it difficult to believe that so many scientists have seemingly accepted the realclimate argument that Preisendorfer’s Rule N applied to a principal components calculation is somehow a substitute for proper statistical analysis. To show the goofiness of this argument, I asked a friend to compile a list of weekly closing prices for 20 […]

Cubasch #2 and Replication #12

Bernd StràƒÆ’à‚⵨er commented that Cubasch told a German radio station about incorrectly located series in MBH98. Does this sound famliar?

Replication #11: the 159 Series

Does anyone remember the 159 series said to have been used in MBH98? Mann et al. [2003] stated: MBH98 calculated PCs of proxy sub-networks separately for each interval in their stepwise reconstruction. This is the only sensible approach, as it allows all data available over each sub-interval to be used. This requires 159 independent time […]

Replication #10: NH Temperature from Archived RPCs

This next replication exercises shows the results of attempting to reconstruct the NH temperature index from the archived RPCs, with the usual puzzling discrepancies.

Replication #9: MBH98 Instrumental Versions

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 […]

Replication #8: Reconstructed PCs

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 […]

Replication #7: Temperature Principal Components

The calculation of temperature PC series needs to be distinguished from the calculation of tree ring PC series. Procedures for the handling of missing data in the temperature dataset were described in the MBH98 Corrigendum SI for the first time in July 2004, specifying that linear interpolation was done, but not specifying the handling of […]

Replication #6: Gridcell Standard Deviations for Temperature Dataset

Gridcell standard deviations for the MBH98 temperature dataset were archived for the first time (together with the temperature dataset) in the Corrigendum SI. Here the difference between detrended and undetrended standard deviations is examined, as well as the difference between using anomalies-new (MBH98) and HadCRU2. Link

Replication #5: the Corrigendum Criterion

The MBH98 Corrigendum purported to explain the discrepancy of 35 series between the series listed in the original SI and the series actually used as follows: These series, all of which come from the International Tree Ring Data Bank (ITRDB), met all the tests used for screening of the ITRDB data used in Mann et […]

Replication #4: Tree Ring Site Selection Criteria

Mann et al. [2000] listed 5 quality control criteria, which were said to have been applied in MBH98 for the inclusion of tree ring sites. These criteria were again referred to in the MBH Corrigendum in July 2004. In total, the information in the SI to MBH98 showed the use of 394 sites, either as […]