Cited by 1,842Advanced Causal Inference TechniquesMonetary Policy and Economic ImpactSpatial and Panel Data Analysis

Testing for Weak Instruments in Linear IV Regression

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Stock, James, Yogo, Motohiro·2002·National Bureau of Economic Research

Abstract

Weak instruments can produce biased IV estimators and hypothesis tests with large size distortions.But what, precisely, are weak instruments, and how does one detect them in practice?This paper proposes quantitative definitions of weak instruments based on the maximum IV estimator bias, or the maximum Wald test size distortion, when there are multiple endogenous regressors.We tabulate critical values that enable using the first-stage F-statistic (or, when there are multiple endogenous regressors, the Cragg-Donald (1993) statistic) to test whether given instruments are weak.A technical contribution is to justify sequential asymptotic approximations for IV statistics with many weak instruments.

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  • As a general rule, if the first-stage F-statistic is greater than 10, the level of weak instrument bias is small.

    “As a general rule, if the first-stage F-statistic is greater than 10, the level of this bias is small.58,59”

    From Mendelian randomization (2022) · cites this paper as [58]

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Authors
Stock, J., & Yogo, M.
Affiliations
National Bureau of Economic Research (US)
Venue
National Bureau of Economic Research
Published
2002-11
OpenAlex
W2110153620
Cited by
1,842
References
32
Citations by year
2026: 122 · 2025: 184 · 2024: 168 · 2023: 101 · 2022: 112 · 2021: 75 · 2020: 96 · 2019: 54 · 2018: 85 · 2017: 42 · 2016: 65 · 2015: 66 · 2014: 93 · 2013: 106 · 2012: 88
Type
report
Language
en
Open access
Locations
National Bureau of Economic Research (publishedVersion)
Funders
National Science Foundation (9730489, 0214131)
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
  • Social Sciences › Economics, Econometrics and Finance › General Economics, Econometrics and Finance › Monetary Policy and Economic Impact
  • Social Sciences › Economics, Econometrics and Finance › Economics and Econometrics › Spatial and Panel Data Analysis
Keywords
weak instruments, instrumental variable regression, critical values

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