To analyze panel data in , you must first ensure the data is in "long" format—where each row represents one observation for a specific entity at a specific time 1. Declaring Panel Data Structure Before using specialized panel commands, you must tell which variable identifies the (e.g., countries, firms) and which identifies (e.g., years). xtset panelvar timevar xtset country year
xtreg wage hours tenure age, fe
xtline creates time-series plots for each panel. The overlay option puts all lines on one graph, perfect for spotting common trends or divergent paths. stata panel data