Abstract Serial correlation in the idiosyncratic errors of panel data models can bias standard errors and lead to invalid inference. The user-written command xtserial (Drukker, 2003) implements a robust test for first-order serial correlation in linear panel-data models with random or fixed effects. This paper provides a comprehensive guide to installing xtserial in Stata, covering both official and alternative methods, addressing common errors, and illustrating the command’s use with an empirical example. 1. Introduction Panel data combine time-series and cross-sectional dimensions, making them rich for analysis but also prone to serial correlation. While Stata’s built-in xtreg post-estimation commands (e.g., xtserial, xthrtest ) offer some diagnostics, the xtserial command—written by David M. Drukker (StataCorp)—provides a direct implementation of the Wooldridge (2002) test for serial correlation. This test is attractive because it works under general conditions and is robust to heteroskedasticity.
. ssc install xtserial, replace checking xtserial consistency and verifying not already installed... installing into C:\Users\jdoe\ado\plus\... downloading xtserial.pkg from http://fmwww.bc.edu/repec/bocode/x/ downloading xtserial.ado done. End of paper xtserial stata install
else display as green "xtserial already installed." Abstract Serial correlation in the idiosyncratic errors of