# Wage regressions: Nominal versus real wage

I'm wondering do I need to convert nominal wages to real wages when running wage equations using panel data sets? My dependent variable is log of wage and I'm looking at returns to education across countries over time. Does the decision to use nominal versus real wage depend on what model I'm using- namely random, fixed effects or pooled OLS?

If, on the other hand, you're comparing wage differentials, say $\log w_s - \log w_u$, where $s$ indicates skill and $u$ indicates unskilled, you do not need to correct for the price level.
$$\log w^s_t - \log w^u_t = \log \frac{w^s_t}{w^u_t} \\ \frac{w^s_t}{w^u_t} = \frac{\frac{w^s_t}{p_t}}{\frac{w^s_t}{p_t}}$$