Library · Causal inference & statistics
What Instrumental Variable Estimation got wrong, from 34 theses
Summary written by a model from the records below: The records examine various empirical challenges encountered when applying instrumental variable estimation across different econometric settings. Researchers frequently faced weak instruments, exclusion restriction violations, and data limitations that hindered reliable causal inference. These records come from graduate theses, 2021 to 2026, each labeled with its degree where the repository states it, and each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.
Plus 8 problems the authors left open, listed at the end.
Failure modes, by theses reporting them
Select a mode to jump to its records.
Weak instruments and low first-stage predictive power undermine estimation
Instruments often displayed weak correlation with endogenous variables, resulting in low first-stage F-statistics and underpowered identification. Consequently, two-stage least squares estimators suffered from substantial loss of precision, biased coefficients, or highly negative goodness of fit metrics.
Tried and failed
instrumental variables with lagged or spatial instruments applied to endogenous peer composition effects. Outcome: no signal. Reason: instruments were weak, producing imprecise estimates compared to ordinary least squares
Three Essays on the Economics of Education · Penn · PhD
Tried and failed
two-stage least squares instrumental variables applied to linear-in-means social peer effects estimation. Outcome: no signal. Reason: Weak instruments caused estimates to lose statistical significance and precision.
Peer Effects and Human Capital Accumulation · Georgia Tech · PhD
Tried and failed
Two-stage least squares instrumental variable regression applied to text sentiment effect on continuous response. Outcome: worse than baseline. Reason: Severe model misspecification or weak instruments leading to highly negative R-squared
Tried and failed
two-stage least squares instrumental variable estimation applied to neighborhood-level crime shock analysis. Outcome: no signal. Reason: The instrument had a weak first stage, failing to sufficiently predict the endogenous variable.
Do criminal groups make or break citizens? How criminal organization presence affects citizen-state interactions · Harvard · PhD
Tried and failed
instrumental variable estimation with regional instruments applied to time-varying technical inefficiency models. Outcome: no signal. Reason: instruments were weak with first-stage F-statistic below threshold and failed to establish endogeneity
Effects of the Free Trade Agreement between the European Union and Ukraine on world trade and production efficiency of Ukrainian sunflower oil · Texas Tech · PhD
Tried and failed
two-stage least squares instrumental variables applied to linear peer effects on clique networks. Outcome: unstable. Reason: weak instruments violate identification relevance in disjoint clique topologies
Weak Identification and Network Measurement Error in Peer Effects Estimation · MIT · PhD
Tried and failed
two-stage least squares instrumental variables estimation applied to dense network peer effect models. Reason: simultaneous weak identification and graph measurement error cause non-vanishing asymptotic bias
Weak Identification and Network Measurement Error in Peer Effects Estimation · MIT · PhD
Tried and failed
unweighted instrumental variable estimation applied to subsample causal inference. Outcome: no signal. Reason: weak instruments with first-stage F-statistic below 10 caused biased and insignificant estimates
Three essays on economics of crime and immigration · Texas Tech · PhD
Tried and failed
historical asset value ratio as instrumental variable applied to agricultural finance econometric estimation. Outcome: no signal. Reason: the instrument was weak with a statistically insignificant first stage relationship
Emerging Questions in Agricultural Finance · Cornell · PhD
Tried and failed
instrumental variable with assignment probability instruments applied to estimating health plan utilization and costs. Outcome: no signal. Reason: instrument lacked sufficient statistical power across subgroups to detect significant differences
Medicaid in ACA Marketplaces : the welfare impact of New Hampshire’s Medicaid experiment · UT Austin · PhD
Considered and rejected
Considered and rejected: Rejected difference GMM due to vulnerability to weak instrumental variable problems.
Essays on Residential Segregation and the Spatial Interaction of Housing and Labor Markets · University at Buffalo · PhD
Considered and rejected
Considered and rejected: Instrumental variable (IV) approach using private company hacks as an instrument for county IT spending ratio to explain bond yield spreads due to being underpowered
Essays in Venture Capital and Corporate Finance · MIT · PhD
Considered and rejected
Considered and rejected: Handpicking instrumental variables or naively using the full set of 1,236 network instruments was rejected in favor of square-root Lasso selection to prevent weak first-stage identification.
Essays in Empirical Operations Management · Cornell · PhD
Plausible and valid instruments are frequently absent or unavailable in observational data
Studies frequently abandoned instrumental variable designs because convincing exogenous instruments could not be found for endogenous variables of interest. Missing data and the absence of clear assignment mechanisms further prevented the practical implementation of causal identification strategies.
Considered and rejected
Considered and rejected: Rejected instrumental variable (IV) approach due to difficulty finding a valid instrument indisputably linking women's micro-business participation to poverty outcomes without failing significance tests.
An Analysis of Women-Owned Micro Business Performance and the Effect on Poverty in the Wolaita Zone, Southern Ethiopia · University College Dublin · PhD
Considered and rejected
Considered and rejected: Instrumental variables were rejected because potential instruments that satisfied exogeneity either had substantial missing data or were absent
Considered and rejected
Considered and rejected: Rejected the instrumental variables (IV) approach due to the non-availability/limitations of finding valid instruments for endogenous director compensation and shareholding variables.
DIRECTORS’ COMPENSATION & FINANCIAL STATEMENT FRAUD: A COMPARATIVE STUDY OF CHINA AND THE US · Nottingham · PhD
Considered and rejected
Considered and rejected: Rejected using instrumental variables to address selection into divorce/separation because no plausible instrument was available in the data.
Women and Children First: Intimate Partner Violence, Children's Well-Being & Child Labour in Ecuador · Dalhousie · PhD
Considered and rejected
Considered and rejected: Rejected regression-based and instrumental variable approaches for FoodAPS analysis due to lack of valid instruments and reliance on extrapolation/model-based assumptions.
Healthy Food Access and Consumption: Informing Interventions Through Analytics · MIT · PhD
Tried and failed
instrumental variable and regression discontinuity designs applied to estimating infection exposure effects. Outcome: data insufficient. Reason: Lack of valid instruments and threshold assignment mechanisms in the observational data
Considered and rejected
Considered and rejected: Decided against Instrumental Variable and Regression Discontinuity designs for Covid-19 primary care analysis due to absent valid instruments and assignment rules.
Estimates exhibit fragility and instability across specifications and functional forms
Instrumental variable estimates frequently failed robustness checks and proved highly sensitive to sample composition, baseline controls, or alternative instrument definitions. In addition, applying linear two-stage least squares to discrete settings yielded unbounded estimates or empty identification sets.
Tried and failed
partial identification using monotone instrumental variables applied to estimating returns to education. Reason: joint monotonicity and instrumental variable assumptions produced empty identified sets refuted by the empirical data
Three essays on applied econometric methods · Iowa State · PhD
Tried and failed
shift-share instrumental variables applied to reduced-form discrete choice regression. Outcome: unstable. Reason: estimates were sensitive to instrument choice and composition of years and industries selected
Essays in Urban Economics · Harvard · PhD
Tried and failed
Linear two-stage least squares instrumental variables applied to binary endogenous variables with binary outcomes. Outcome: unstable. Reason: Produced unbounded and inefficient estimates when modelling binary treatment and binary outcome relationships
Frail patients’ hospital resource use, outcomes, and care transitions - An analysis of the English NHS · Imperial · PhD
Tried and failed
instrumental variable estimation applied to childcare labor employment responses. Outcome: unstable. Reason: empirical results failed standard sensitivity and robustness checks
Essays in Macroeconomics and Labor Economics · Harvard · PhD
Considered and rejected
Considered and rejected: Rejected ordinary least squares (OLS) regression for the first stage of the instrumental variable model in favor of a binomial regression with logit link to ensure non-negative predicted online shopping percentages
Essays on Sustainability in Agriculture and Food Systems · MIT · PhD
Tried and failed
two-stage least squares instrumental variable regression applied to estimating neighborhood collective action spillover effects. Outcome: did not generalise. Reason: estimates were not robust to controlling for baseline outcome rates
Managing the "Water Pressure": The Political Economy of Urban Service Provision · Harvard · PhD
Tried and failed
alternative instrumental variable specification applied to estimating debt effect on earnings. Outcome: no signal. Reason: the estimated causal effect lost statistical significance and diminished towards zero under the alternative instrument
Essays on student debt, unemployment, and labor market outcomes · UT Austin · PhD
Violations of the exclusion restriction invalidate causal identification
Instrumental variable models were rejected or failed when candidate instruments directly affected outcomes or correlated with omitted geographic and historical confounders. Placebo tests and institutional mechanisms demonstrated that instruments failed to satisfy strict exogeneity requirements.
Considered and rejected
Considered and rejected: Rejected simultaneous equation / instrumental variable causal inference modeling due to the lack of a defensible exclusion restriction.
Rising powers, subordinate monopolization, and major interstate war · Oxford · PhD
Tried and failed
instrumental variable selection using exclusion restriction applied to linear outcome equation in selection model. Reason: omitted historical and geographic confounders violated the exclusion restriction
Essays on Interviews and Matching · MIT · PhD
Tried and failed
instrumental variable regression with placebo test applied to health facility access causal estimation. Reason: instrument violated exclusion restriction yielding implausible non-zero effect on predetermined adult height
Essays on maternal and child health in India · UT Austin · PhD
Considered and rejected
Considered and rejected: Rejected Instrumental Variables (IV) approach using universal FAFSA policy adoption as an instrument for college enrollment because counselor advising violates the exclusion restriction.
Essays in the Economics of Education · Harvard · PhD
Considered and rejected
Considered and rejected: Rejected conventional Instrumental Variables (LATE) for persuasive ad experiments due to implausibility of the exclusion restriction.
Messy Measurement: Approaches to Causal Inference With Unobserved Variables · MIT · PhD
Measurement error and factor projection methods induce estimator bias
Unaddressed measurement error and missing data caused severe bias, inconsistency, and sign reversals in instrumental variable regressions. Furthermore, incorporating additional principal component factors into panel models systematically increased bias toward standard two-stage least squares.
Tried and failed
ordinary least squares and instrumental variable regression applied to data with measurement error and missingness. Outcome: unstable. Reason: unmodeled measurement error and missing data caused severe bias and frequent sign reversals in parameter estimates
Essays on Econometrics, Causal Inference, and Machine Learning · MIT · PhD
Tried and failed
two-stage least squares with dichotomized noisy proxy applied to causal compliance effect estimation. Reason: measurement error correlated with the instrumental variable, inducing bias and inconsistency in effect estimates
Causal Inference with Measurement Errors: with Applications to Experimental and Observational Studies · MIT · PhD
Tried and failed
direct PCA factor projection applied to instrumental variable panel data. Reason: estimator bias increases toward standard two-stage least squares as more factor components are included
Essays on the Effects of Immigration on Labor Markets · MIT · PhD
Tried and failed
iterative PCA factor structure estimation applied to panel instrumental variables causal estimation. Outcome: worse than baseline. Reason: increasing the estimated factor count introduced bias towards standard two-stage least squares
Essays on Econometrics and Policy Evaluation · MIT · PhD
Left open by the authors
Problems the authors named and did not get to.
Left open
Identify an exogenous instrument for labor market participation to estimate earnings impacts of teen childbearing via MTE. Blocker: Requires discovering a novel, valid instrumental variable for endogenous labor market selection
ESSAYS ON THE INTERGENERATIONAL TRANSMISSION OF HUMAN CAPITAL AND SOCIOECONOMIC STATUS · Cornell · PhD
Left open
Estimate the causal effect of education on lifetime completed fertility using instrumental variables on older women census or survey cohorts. Blocker: None
Three essays on factors influencing changes in labor and marriage markets · Iowa State · PhD
Left open
Replicate promise program expectation findings using a longer longitudinal panel or instrumental variables strategy to formally test parallel trends. Blocker: Requires access to longitudinal education survey or administrative data tracking promise program eligibility and expectations.
Three Essays In Economics, Education Policy, And Inequality · Penn · PhD
Left open
Develop an instrumental variable strategy to resolve endogeneity and reverse causality in micro-neighborhood ethnic demography spatial econometric models. Blocker: Finding a theoretically valid, exogenous instrument for micro-neighborhood level ethnic residential sorting in Kenya is an open econometric identification challenge.
Safety in Separation? Ethnic Demography and Violence in Kenya · Cornell · PhD
Left open
Perform an instrumental variables analysis instrumenting the decision to share news diet summaries with disclosure treatment status using experiment data. Blocker: Requires private field experiment data collected on Twitter/X by the thesis author.
Essays on Political Economy · MIT · PhD
Left open
Estimate heterogeneous treatment effects of inpatient physician consults across patient, provider, and setting subgroups using quasi-experimental instrumental variable methods. Blocker: Requires private hospital electronic health record or claims data used in the thesis.
Essays on Physician Consults · Penn · PhD
Left open
Disentangle the causal health impacts of concurrent pollutants like O3, SO2, NO2, and CO from PM2.5 using distributed lag instrumental variable models. Blocker: Lack of a specified econometric identification strategy or valid instrumental variables for multiple simultaneous pollutants.
Essays on Environmental and Urban Economics · Cornell · PhD
Left open
Implement a delta-method standard error and a fully joint two-stage difference-in-differences instrumental variable (2SDD-IV) event-study estimator. Blocker: None
Competition and Regulation in Medicare Advantage · Harvard · PhD
Who has worked on this
Authors of the public theses cited on this page, most-cited first.
- Sandeepa Arora · Imperial · PhD · 2025
Exploring and enhancing the research potential of an integrated health care database: an observational study using de-identified linked, routine data for children and young people in Northwest London - William Wei Wang · MIT · PhD · 2025
Weak Identification and Network Measurement Error in Peer Effects Estimation - Joseph Guillermo Pinete Hnath · Harvard · PhD · 2026
Competition and Regulation in Medicare Advantage - Rachel Pomerantz · Harvard · PhD · 2026
Essays in Macroeconomics and Labor Economics - Zach Weingarten · Penn · PhD · 2026
Three Essays on the Economics of Education - Salman Khan · Harvard · PhD · 2025
Essays in the Economics of Education - Fiona Paine · MIT · PhD · 2025
Essays in Venture Capital and Corporate Finance - Ahmet Gulek · MIT · PhD · 2025
Essays on the Effects of Immigration on Labor Markets - Jaume Vives-i-Bastida · MIT · PhD · 2025
Essays on Econometrics and Policy Evaluation - Xinming Liu · MIT · PhD · 2025
Essays on Sustainability in Agriculture and Food Systems - A Qadri · Oxford · PhD · 2025
Unveiling dynamics: examining the gendered association between shifting work patterns, labour market changes, and maternity leave on mental health and well-being. - Zachary Templeton · Penn · PhD · 2025
Essays on Physician Consults
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