How do scientists know their data-processing techniques are reliable?

The records of global temperatures calculated by U.S. and other major climate research organizations are remarkably similar, despite the different data-processing techniques used. The techniques used by NASA's Goddard Institute for Space Studies (GISS), National Climatic Data Center (NCDC), and other respected groups, such as the British Meteorological Office's Hadley Centre/Climatic Research Unit of the University of East Anglia (CRU) and the Australian Bureau of Meteorology, are peer-reviewed, and the processed data sets have undergone many peer-reviewed analyses as well.

An independent nonprofit organization called Berkeley Earth, funded by educational grants, has devised its own data-processing techniques to deal with the changes listed above. Again, the results are very similar to results from NCDC, GISS, and the CRU.