The basic results of the APO analysis are summarized for over three different periods in table 6. A simple comparison with the original TDRI study is available in column (3) for the 1977-90 period. Outside of some downward revisions in the estimated output growth rate, the most significant change was in the estimate of quality improvements for the labor input; they find a contribution of 0.7 percent per year to growth compared to 1.5 percent in the TDRI study. While the methodologies are similar, the APO group’s result seems more plausible. No explanation for the differences is provided in the paper. The change falls through to the estimate of TFP growth which is increased from 1.2 percent per year in the TDRI study to an average of 1.8 percent.