Research Discussion Paper – 1974 Equation (A.18)

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