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Power Bounds and Efficiency Loss for Asymptotically Optimal Tests in IV Regression

Marcelo J. Moreira, Geert Ridder, Mahrad Sharifvaghefi

arXiv 22 Mar 2026 · Econometrics

arXiv:2603.21004 · PDF · OpenAlex · Extracted main text

Abstract

We characterize the maximal attainable power-size gap in overidentified instrumental variables models with heteroskedastic or autocorrelated (HAC) errors. Using total variation distance and Kraft's theorem, we define the decision theoretic frontier of the testing problem. We show that Lagrange multiplier and conditional quasi likelihood ratio tests can have power arbitrarily close to size even when the null and alternative are well separated, because they do not fully exploit the reduced-form likelihood. In contrast, the conditional likelihood ratio (CLR) test uses the full reduced-form likelihood. We prove that the power-size gap of CLR converges to one if and only if the testing problem becomes trivial in total variation distance, so that CLR attains the decision theoretic frontier whenever any test can. An empirical illustration based on Yogo (2004) shows that these failures arise in empirically relevant configurations.

Citation extraction

24
references
50
in-text mentions
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distinct cited
7
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9,384
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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Kraft,C Some Conditions for Consistency and Uniform Consistency of Statistical Procedures1.00093100%
2Andrews, D. W. K. and M. J. Moreira and J. H. Stock (2006) Optimal Two-Sided Invariant Similar Tests for Instrumental Variables Regression self0.92843100%
3Motohiro Yogo Estimating the Elasticity of Intertemporal Rate of Substitution When Instruments Are Weak0.92843100%
4Isaiah Andrews Conditional Linear Combination Tests for Weakly Identified Models0.84333100%
5H. Moreira and M. J. Moreira Optimal Two-Sided Tests for Instrumental Variables Regression with Heteroskedastic and Autocorrelated Errors self0.84333100%
6Moreira, M. J A Conditional Likelihood Ratio Test for Structural Models self0.73732100%
7Staiger, D. and J. H. Stock Instrumental Variables Regression with Weak Instruments0.73732100%
8Isaiah Andrews and Anna Mikusheva Conditional Inference with a Functional Nuisance Parameter0.64422100%
9M. Bertanha and M.J. Moreira Impossible Inference in Econometrics: Theory and Applications self0.64422100%
10Dufour, J-M Some Impossibility Theorems in Econometrics with Applications to Structural and Dynamic Models0.58531100%

Showing the top 10 of 24 scored citations.

Cited by, within the corpus

arXiv econ.EM papers that cite this one, ranked by how heavily they lean on it.

Citing paperIntensityMentionsSections
1Properties of the Conditional Likelihood Ratio Test under Discrete Approximation0.64422