The TDRI study includes two important extensions of the prior research. The first
contribution was the construction of an index of changes in the quality of labor. The labor force
survey is used to separate workers cross-classified by age, gender and education; and for each of
these groups they are able to calculate an average wage rate. With that information, they
construct an index of labor quality that uses relative wages to value changes in the gender, age,
and educational level of the workforce. Their calculations imply an improvement in the quality