McIntyre & McKittrick's papers were cited by Senator Jim Inhofe and Representative Joe Barton to support their political criticisms of the MBH studies, and Representative Sherwood Boehlert requested the National Academy of Sciences in the United States to arrange an investigation. The outcome was the North Report, published in 2006, which endorsed the MBH studies with a few reservations. The principal component analysis method criticised by McIntyre & McKittrick had a small tendency to bias results so was not recommended, but it had little influence on the final reconstructions, and other methods produced similar results.