Mann Criticizes Mann 08 For Data Quality Errors!
September 23, 2010Posted by on
No I’m not making that up for that is what Dr. Michael Mann has done in his attempt to refute the Mcshane & Wyner paper (MW 10). Dr. Mann in conjunction with Dr Gavin Schmidt and Dr. Rutherford written a comment to the MW 10 paper and the Journal of Applied Statistics has accept it for print, however it wasn’t a very good critic of the MW 10 paper because one of the points they make is that:
However, the absence of both proper data quality control and appropriate “pseudoproxy” tests to assess the performance of their methods invalidate their main conclusions.
Now if you had read the MW10 paper the issue of data quality control was explicitly handled this way:
We are not interested at this stage in engaging the issues of data quality. To wit, henceforth and for the remainder of the paper, we work entirely with the data from Mann et al. (2008)3. This is by far the most comprehensive publicly available database of temperatures and proxies collected to date. It contains 1,209 climate proxies (with some going back as far as 8855 BC and some continuing up till 2003 AD). It also contains a database of eight global annual temperature aggregates dating 1850-2006 AD (expressed as deviations or ”anomalies” from the 1961-1990 AD average4). Finally, there is a database of 1,732 local annual temperatures dating 1850-2006 AD (also expressed as anomalies from the 1961-1990 AD average)5. All three of these datasets have been substantially processed including smoothing and imputation of missing data (Mann et al., 2008). While these present interesting problems, they are not the focus of our inquiry. We assume that the data selection, collection, and processing performed by climate scientists meets the standards of their discipline. Without taking a position on these data quality issues, we thus take the dataset as given.
Now as you can see if there is any data quality issues in the data made publicly available then it is the responsibility of the Climate Scientist that made the database, McShane and Wyner started their paper a priori that the Climate Scientist knew what he/she was doing when sampling, collecting and data quality was performed (processing). Now who was the Climate Scientist that did the processing of the data in the data base and responsible for its quality? Dr. Michael Mann.
In conclusion for Dr. Mann to now claim that the data used by McShane & Wyner was of poor quality, he is actually admitting that the data in the Mann 08 paper is poor and wasn’t handled properly. Thus by criticizing the MW 10 paper he actually criticizes himself and Mann 08, because the data used in MW10 is nothing more then the data used in Mann 08.
You can read the MW paper here:
You can read the Mann/Schmidt/Rutherford comment here: