Research Discussion Paper – 1974 Equation (A.20)

\begin{array}{l} DL = F (\frac{WE (1 + TP)}{PN (1 - TI)}, \frac{PT}{PN}, Q) \\ \begin{array}{l} F_{1} < 0 & F_{2} > 0 & F_{3} \end{array} > 0 \end{array}