Visualizing trends is crucial before modeling.

* Plot a single variable over time for all units (spaghetti plot)
xtline gdp
xtreg wage hours tenure age i.year, re

Stata ships with example datasets. For panel data, the most famous is nlswork.dta (National Longitudinal Survey of Young Women, 1968–1988).

webuse nlswork, clear

This dataset contains 28,534 observations on 4,711 individuals (ID variable: idcode) across up to 12 years.


xtreg wage hours tenure, fe robust

or

xtreg wage hours tenure, fe vce(cluster idcode)

Already achieved with i.year in the FE model.

Alternative to RE. Does not model the individual effect explicitly but accounts for the correlation structure within panels.

For interpretation, compute marginal effects:

margins, dydx(experience) at(union=(0 1))