from https://www.econometrics-with-r.org/12.6-exercises-12.html

2. The variable distance (the distance to the closest 4-year college in 10 miles) will serve as an instrument later in the exercise. Use a histogram to visualize the distribution of distance. The function hist() can be used to generate histograms.

3. Regress the logarithm of wage on education, that is, estimate the model: log(wage_i)=₀+₁education_i+u_i and save the result to wage_mod_1.

4. Run another model which includes the regressors unemp, ethnicity, gender and urban. Save the result to wage_mod_2

7. Gather all four models into a table with RSEs

8. Interpret the results

9. Evaluate the IV for relevance and exogeneity