RDP 2007-10: Trade Costs and Some Puzzles in International Macroeconomics Equation (5)

\begin{array}{l} \frac{I_{i t}}{Y_{i t}} = δ_{1 i} + ϕ_{1} \frac{S_{i t}}{Y_{i t}} + γ_{1} \frac{S_{i t}}{Y_{i t}} f_{i t} + θ_{1} f_{i t} + ϖ_{1} K_{i t} \\ + ϖ_{2} K_{i t} f_{i t} + ϖ_{3} K_{i t} f_{i t} \frac{S_{i t}}{Y_{i t}} + ϖ_{4} K_{i t} \frac{S_{i t}}{Y_{i t}} + e_{1 i t} \end{array}