The article compares different ways to measure total factor productivity growth. They looked at Solow's residual analysis, the Index Number Approach, Input-Output Analysis, and Data Envelopment Analysis. These methods have different assumptions but can be compared to each other. The researchers used the Solow Residual as a benchmark for their comparisons. By looking at how these methods relate to each other, they were able to understand the differences between them. Ultimately, they put all four measures into a common framework.