# XTSEL: Stata module for selection of variables and specification in a panel-data framework

*Alfonso Ugarte-Ruiz* ()

Statistical Software Components from Boston College Department of Economics

**Abstract:**
The package XTSEL includes two new commands (xtselvar and xtselmod) that help us to rank the best predictors between a number of alternative explanatory variables (candidates), or the best specification between all possible combinations of a set of explanatory variables, according to several in-sample and out-of-sample statistics. They are specially adapted for a panel data framework, firstly because the out-of-sample prediction performance is measured in the two inherent dimensions of a panel (time-series and cross-individuals), and secondly because they allow a large number of methodological options that typically are necessary in panel data analysis. Given a set of n predictors, xtselvar estimates the same specification n times, one for each predictor. xtselmod estimates 2^n - 1 different specifications, one per each possible combination out of the set of n variables. Both procedures keep constant the same dependent variable and an optional list of fixed control variables, plus several other methodological options. For each candidate variable/specification, the procedures estimate a set of parameters and statistical criteria: 1. Adjusted R squared (R2_ad). 2. Akaike Information Criterion (AIC). 3. Bayesian Information Criterion (BIC) 4. U-Theil in time-series dimension: RMSE of variable/specification vs. RMSE from a naïve prediction or an AR1 model (Uth_TS). 5. U-Theil in cross-section dimension: RMSE of variable/specification vs. RMSE from a naïve prediction or an AR1 model (Uth_CS). Both commands rank each variable/specification according to each criterion and generate one ranking per each one of them. xtselvar also reports coefficients and t-statistic of each candidate variable. They also compute a composite ranking summarizing all five criteria. They finally sort all candidate variables/specifications according to the selected ranking, which by default is the composite ranking.

**Language:** Stata

**Requires:** Stata version 12

**Keywords:** panel data; specification; variable selection (search for similar items in EconPapers)

**Date:** 2020-07-24, Revised 2022-11-11

**Note:** This module should be installed from within Stata by typing "ssc install xtsel". The module is made available under terms of the GPL v3 (https://www.gnu.org/licenses/gpl-3.0.txt). Windows users should not attempt to download these files with a web browser.

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**Downloads:** (external link)

http://fmwww.bc.edu/repec/bocode/x/xtselmod.ado program code (text/plain)

http://fmwww.bc.edu/repec/bocode/x/xtsel.sthlp help file (text/plain)

http://fmwww.bc.edu/repec/bocode/x/xtselmod.sthlp help file (text/plain)

http://fmwww.bc.edu/repec/bocode/x/xtselvar.ado program code (text/plain)

http://fmwww.bc.edu/repec/bocode/x/xtselvar.sthlp help file (text/plain)

http://fmwww.bc.edu/repec/bocode/p/panelexample.dta sample data file (application/x-stata)

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**Persistent link:** https://EconPapers.repec.org/RePEc:boc:bocode:s458816

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