arXiv subjects

Amrei Stammann

Publications and source records attributed to Amrei Stammann.

9 recordsLinked to original sources

arXiv2026

Inference for Fixed Effects Estimators when Panels are Unbalanced

We develop the asymptotic theory for two-way fixed effects M-estimators in unbalanced panels, within a framework where both panel dimensions grow large at proportional rates. The selection process may be deterministic, stochastic, or a combination of the two. We require neither a missing-at-random condition nor a selection equation, only a conditional mean restriction on the outcome. The uncorrected estimators are asymptotically normal but not correctly centered due to incidental parameter bias and feedback bias. The latter arises when regressors or the selection indicator respond to past outcomes. We propose debiased estimators that remove both biases without requiring knowledge of which regressors or selection components are predetermined. Simulations show that the corrections remove most of the bias and restore coverage close to nominal levels. Revisiting a study on capital inflow surges and banking crises, we find that the corrections leave qualitative conclusions unchanged but substantially shift the estimated magnitudes.

econ.EM↗

arXiv2026

Inference in Unbalanced Panel Data Models with Interactive Fixed Effects

We derive the asymptotic theory of Bai (2009)'s interactive fixed effects estimator for unbalanced panels in which the source of attrition is conditionally random. For inference, we propose a method of alternating projections algorithm based on straightforward scalar expressions to compute the residualized variables required for bias correction and covariance matrix estimation. Simulation experiments confirm that our asymptotic results provide reliable finite-sample approximations. We also reassess Acemoglu et al. (2019). Allowing for a more general form of unobserved heterogeneity, we confirm significant effects of democratization on economic growth.

econ.EM↗

arXiv2025

(Debiased) Inference for Fixed Effects Estimators with Three-Dimensional Panel and Network Data

Inference for fixed effects estimators is often unreliable due to Nickell- and incidental parameter biases. While these issues are well understood for classical two-dimensional panels, little is known about three-dimensional panel structures (e.g., sender x receiver x time). We develop inferential theory for a broad class of linear and nonlinear fixed effects M-estimators in this setting, covering bipartite, directed, and undirected network panel data, multiple specifications of additively separable unobserved effects, and both strictly exogenous and predetermined regressors. Our analysis reveals fundamentally different asymptotic properties compared to two-dimensional panels. In particular, we find a sharp dichotomy across specifications: (i) when unobserved effects vary along a single panel dimension, estimators are asymptotically unbiased, (ii) when they vary along two panel dimensions, estimators may suffer from a severe inference problem characterized by a degenerate asymptotic distribution. We resolve the latter by deriving explicit bias formulas and proposing analytically debiased estimators with nondegenerate, correctly centered asymptotic distributions. An empirical application studies dynamic network formation in a directed panel of bilateral trade relationships.

econ.EM↗

arXiv2025

The Effects of Flipped Classrooms in Higher Education: A Causal Machine Learning Analysis

This study uses double/debiased machine learning (DML) to evaluate the impact of transitioning from lecture-based blended teaching to a flipped classroom concept. Our findings indicate effects on students' self-conception, procrastination, and enjoyment. We do not find significant positive effects on exam scores, passing rates, or knowledge retention. This can be explained by the insufficient use of the instructional approach that we can identify with uniquely detailed usage data and highlights the need for additional teaching strategies. Methodologically, we propose a powerful DML approach that acknowledges the latent structure inherent in Likert scale variables and, hence, aligns with psychometric principles.

econ.GN↗

arXiv2023

Debiased Fixed Effects Estimation of Binary Logit Models with Three-Dimensional Panel Data

Naive maximum likelihood estimation of binary logit models with fixed effects leads to unreliable inference due to the incidental parameter problem. We study the case of three-dimensional panel data, where the model includes three sets of additive and overlapping unobserved effects. This encompasses models for network panel data, where senders and receivers maintain bilateral relationships over time, and fixed effects account for unobserved heterogeneity at the sender-time, receiver-time, and sender-receiver levels. In an asymptotic framework, where all three panel dimensions grow large at constant relative rates, we characterize the leading bias of the naive estimator. The inference problem we identify is particularly severe, as it is not possible to balance the order of the bias and the standard deviation. As a consequence, the naive estimator has a degenerating asymptotic distribution, which exacerbates the inference problem relative to other fixed effects estimators studied in the literature. To resolve the inference problem, we derive explicit expressions to debias the fixed effects estimator.

econ.EM↗

arXiv2022

Latent Unbalancedness in Three-Way Gravity Models

Many panel data sets used for pseudo-poisson estimation of three-way gravity models are implicitly unbalanced because uninformative observations are redundant for the estimation. We show with real data as well as simulations that this phenomenon, which we call latent unbalancedness, amplifies the inference problem recently studied by Weidner and Zylkin (2021).

econ.EM↗

arXiv2021

State Dependence and Unobserved Heterogeneity in the Extensive Margin of Trade

We study the role and drivers of persistence in the extensive margin of bilateral trade. Motivated by a stylized heterogeneous firms model of international trade with market entry costs, we consider dynamic three-way fixed effects binary choice models and study the corresponding incidental parameter problem. The standard maximum likelihood estimator is consistent under asymptotics where all panel dimensions grow at a constant rate, but it has an asymptotic bias in its limiting distribution, invalidating inference even in situations where the bias appears to be small. Thus, we propose two different bias-corrected estimators. Monte Carlo simulations confirm their desirable statistical properties. We apply these estimators in a reassessment of the most commonly studied determinants of the extensive margin of trade. Both true state dependence and unobserved heterogeneity contribute considerably to trade persistence and taking this persistence into account matters significantly in identifying the effects of trade policies on the extensive margin.

econ.EM↗

arXiv2020

Fixed Effects Binary Choice Models: Estimation and Inference with Long Panels

Empirical economists are often deterred from the application of fixed effects binary choice models mainly for two reasons: the incidental parameter problem and the computational challenge even in moderately large panels. Using the example of binary choice models with individual and time fixed effects, we show how both issues can be alleviated by combining asymptotic bias corrections with computational advances. Because unbalancedness is often encountered in applied work, we investigate its consequences on the finite sample properties of various (bias corrected) estimators. In simulation experiments we find that analytical bias corrections perform particularly well, whereas split-panel jackknife estimators can be severely biased in unbalanced panels.

econ.EM↗

arXiv2018

Fast and Feasible Estimation of Generalized Linear Models with High-Dimensional k-way Fixed Effects

We present a fast and memory efficient algorithm for the estimation of generalized linear models with an additive separable k-way error component. The brute force approach uses dummy variables to account for the unobserved heterogeneity, but quickly faces computational limits. Thus, we show how a weighted version of the Frisch-Waugh-Lovell theorem combined with the method of alternating projections can be incorporated into a Newton-Raphson algorithm to dramatically reduce the computational costs. The algorithm is especially useful in situations, where generalized linear models with k-way fixed effects based on dummy variables are computationally demanding or even infeasible due to time or memory limitations. In a simulation study and an empirical application we demonstrate the performance of our algorithm.

stat.AP↗