Arbeitspapier

Fixed Effects and Causal Inference

Across many disciplines, the fixed effects estimator of linear panel data models is the default method to estimate causal effects with nonexperimental data that are not confounded by time-invariant, unit-specific heterogeneity. One feature of the fixed effects estimator, however, is often overlooked in practice: With data over time t ∈ {1,...,T} for each unit of observation i ∈ {1,...,N}, the amount of unobserved heterogeneity the researcher can remove with unit fixed effects is weakly decreasing in T. Put differently, the set of attributes that are time-invariant is not invariant to the length of the panel. We consider several alternatives to the fixed effects estimator with T > 2 when relevant unit-specific heterogeneity is not time-invariant, including existing estimators such as the first-difference, twice first-differenced, and interactive fixed effects estimators. We also introduce several novel algorithms based on rolling estimators. In the situations considered here, there is little to be gained and much to lose by using the fixed effects estimator. We recommend reporting the results from multiple linear panel data estimators in applied research.

Sprache
Englisch

Erschienen in
Series: IZA Discussion Papers ; No. 16202

Klassifikation
Wirtschaft
Single Equation Models; Single Variables: Panel Data Models; Spatio-temporal Models
Model Construction and Estimation
Model Evaluation, Validation, and Selection
Thema
panel data
fixed effects
first-differences
interactive fixed effects
unobserved heterogeneity
time-varying individual effects

Ereignis
Geistige Schöpfung
(wer)
Millimet, Daniel L.
Bellemare, Marc
Ereignis
Veröffentlichung
(wer)
Institute of Labor Economics (IZA)
(wo)
Bonn
(wann)
2023

Handle
Letzte Aktualisierung
10.03.2025, 11:45 MEZ

Datenpartner

Dieses Objekt wird bereitgestellt von:
ZBW - Deutsche Zentralbibliothek für Wirtschaftswissenschaften - Leibniz-Informationszentrum Wirtschaft. Bei Fragen zum Objekt wenden Sie sich bitte an den Datenpartner.

Objekttyp

  • Arbeitspapier

Beteiligte

  • Millimet, Daniel L.
  • Bellemare, Marc
  • Institute of Labor Economics (IZA)

Entstanden

  • 2023

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