About

John C. Chao is a Professor of Economics at the University of Maryland. His research interests focus on econometric methods, particularly in the areas of many instruments, panel data models, and time series econometrics. He is based in the Department of Economics at the University of Maryland, College Park, where he holds office in Tydings Hall. Professor Chao's work contributes to the advancement of econometric techniques used to analyze complex economic data structures, emphasizing the development and application of models that handle multiple instruments and dynamic data over time.

Research topics

• Computer Science
• Mathematics
• Statistics
• Econometrics
• Medicine
• Engineering
• Surgery
• General surgery

Selected publications

• Comparison of Intramedullary Screw Fixation, Plating, and K-Wires for Metacarpal Fracture Fixation: A Meta-Analysis

  Hand · 2024-02-27 · 13 citations

  reviewOpen access

  BACKGROUND: Metacarpal fractures are common injuries with multiple options for fixation. Our purpose was to compare outcomes in metacarpal fractures treated with intramedullary screw fixation (IMF), Kirschner wires (K-wires), or plating. METHODS: A systematic literature review using the MEDLINE database was performed for studies investigating metacarpal fractures treated with IMF, plating, or K-wires. We identified 34 studies (9 IMF, 8 plating, 17 K-wires). A meta-analysis using both mixed and fixed effects models was performed. Outcome measures included mean Disabilities of the Arm, Shoulder, and Hand (DASH) scores, total active motion (TAM), grip strength, time to radiographic healing, and rates of infection and reoperation. RESULTS: Patients with IMF had significantly lower DASH scores (0.6 [95% confidence interval [CI], 0.2-1.0]) compared with K-wires (7.4 [4.8-9.9]) and plating (9.8 [5.3-14.3]). Intramedullary screw fixation also had significantly lower rates of reoperation (4%, [2%-7%]), compared with K-wires (11% [7%-16%]) and plating (11% [0.07-0.17]). Grip strength was significantly higher in IMF (104.4% [97.0-111.8]) compared with K-wires (88.5%, [88.3-88.7]) and plating (90.3%, [85.4-95.2]). Mean odds ratio time was similar between IMF (21.0 minutes [10.4-31.6]) and K-wires (20.8 minutes [14.0-27.6]), but both were shorter compared with plating (52.6 minutes [33.1-72.1]). There were no statistically significant differences in time to radiographic healing, TAM, or rates of reoperation or infection. CONCLUSIONS: This meta-analysis compared the outcomes of metacarpal fixation with IMF, K-wires, or plating. Intramedullary screw fixation provided statistically significant lower DASH scores, higher grip strength, and lower rates of reoperation, suggesting that it is a comparable method of fixation to K-wires and plating for metacarpal fractures.

  PublisherOA PDFDOI

• A Case of Upper Extremity Gangrene Likely Secondary to Mucormycosis.

  PubMed · 2024

  • Medicine
  • Surgery
  • General surgery

  Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of ePlasty or HMP Global, their employees, and a iliates.Questions 1.What is the epidemiology and pathology of a mucormycosis infection of the upper extremity?2. What are some risk factors, signs, and symptoms associated with mucormycosis infections of the upper extremity?3. What is the surgical management of a mucormycosis infection of the upper extremity?4. What is the likely outcome of a secondary cutaneous mucormycosis infection? Case DescriptionA 77-year-old male with a medical history of benign prostatic hyperplasia, neurogenic bladder with chronic indwelling catheter, hypertension, diabetes type 2 (hemoglobin A1c of 5.9 at 1 month prior to presentation), extensive coronary and arterial disease, and heart failure with reduced ejection fraction presented to our service with a 9-day history of a black, gangrenous left middle finger (Figure 1).Purulence was not encountered upon initial consultation.

  PublisherOA PDF

• Jackknife estimation of a cluster-sample IV regression model with many weak instruments

  Journal of Econometrics · 2023 · 4 citations

  1st authorCorresponding
  • Computer Science
  • Mathematics
  • Statistics
  PublisherDOI

• Comparison of Intramedullary Screws, Plating, and K-Wires for Metacarpal Fracture Fixation: A Meta-analysis

  Plastic & Reconstructive Surgery Global Open · 2022-10-01 · 1 citations

  articleOpen access1st authorCorresponding

  PURPOSE: Metacarpal fractures are common injuries with multiple options for fixation, including plating and screws, K-wires, and intramedullary screws. Our purpose was to compare outcomes, including DASH score, total active motion (TAM), grip strength, and rates of re-operation or infection, in metacarpal fractures treated with intramedullary screw fixation (IMF), K-wires, or plates/screws. METHOD: A systematic literature review using the MEDLINE Database was performed for studies investigating metacarpal fractures treated with IMF, plates/screw, or K-wires. We identified nine studies using IMF, eight using plates/screws, and 17 using K-wires. A meta-analysis using random or fixed effects models was performed to calculate pooled effect size estimates, controlling for heterogeneity between studies. Outcome measures included mean DASH scores, mean TAM, mean grip strength (percentage to contralateral), mean time to radiographic healing, and the proportion of patients with infection and re-operation. RESULTS: Patients with IMF of metacarpal fractures had significantly lower mean DASH scores at an average of 0.6 [95% CI: 0.2, 1.0] compared to both K-wire (7.4 [4.8, 9.9]) and plates/screws (9.8 [5.3, 14.3]) (both p<0.001). IMF also had significantly lower rates of reoperation at 4% [2%, 7%], compared to K-wires 11% [7%, 16%], p= 0.001 and plate/screw fixation at 11% [0.07, 0.17] p=0.01. Grip strength was significantly higher in IMF (104.4% [97.0, 111.8]) compared to K-wires (88.5%, [88.3, 88.7]) and plate/screws (90.3, [85.4, 95.2] (both p<0.001). There were no statistically significant differences in time to radiographic healing of evidence, mean TAM, or rates of infection. Mean OR time was similar between IMF (average of 21.0 minutes [10.4, 31.6]) and K-wires (20.8 minutes [14.0, 27.6]), but both were shorter compared to plate/screw fixation (average 52.6 minutes [33.1, 72.1]) with K wires being significantly shorter (p<0.001). Summary This meta-analysis compares outcomes of metacarpal fixation with IMF, K-wires, or plates/screws. IMF provided statistically significant lower DASH scores, higher grip strength, lower rates of re-operation, when compared to K-wires and plates/screws for fixation of metacarpal fractures. There were no statistically significant differences in rates of mean TAM, time to radiographic healing, or rates of infection between the 3 groups. OR time was lower for both IMF and K wires as compared to plates and screws, but only K wires had enough data points for significance. CONCLUSION: Intramedullary screw fixation of metacarpal fractures provides lower DASH scores, higher grip strength, and lower rates of re-operation when compared to K-wires and plates/screws.

  PublisherDOI

• Selecting the Relevant Variables for Factor Estimation in FAVAR Models

  SSRN Electronic Journal · 2022 · 3 citations

  1st authorCorresponding
  • Computer Science
  • Computer Science
  • Econometrics
  PublisherDOI

• Consistent Estimation, Variable Selection, and Forecasting in FAVAR Models

  SSRN Electronic Journal · 2022-01-01

  articleOpen access1st authorCorresponding
  PublisherDOI

• Technical Appendix to Consistent Estimation, Variable Selection, and Forecasting in FAVAR Models

  SSRN Electronic Journal · 2022-01-01

  articleOpen access1st authorCorresponding
  PublisherDOI

• Jackknife Estimation of a Cluster-Sample IV Regression Model with Many Weak Instruments

  SSRN Electronic Journal · 2021-01-01 · 1 citations

  articleOpen access1st authorCorresponding
  PublisherDOI

• Uniform Inference in Panel Autoregression

  Econometrics · 2019-11-26 · 2 citations

  articleOpen access1st authorCorresponding

  This paper considers estimation and inference concerning the autoregressive coefficient ( ρ ) in a panel autoregression for which the degree of persistence in the time dimension is unknown. Our main objective is to construct confidence intervals for ρ that are asymptotically valid, having asymptotic coverage probability at least that of the nominal level uniformly over the parameter space. The starting point for our confidence procedure is the estimating equation of the Anderson–Hsiao (AH) IV procedure. It is well known that the AH IV estimation suffers from weak instrumentation when ρ is near unity. But it is not so well known that AH IV estimation is still consistent when ρ = 1 . In fact, the AH estimating equation is very well-centered and is an unbiased estimating equation in the sense of Durbin (1960), a feature that is especially useful in confidence interval construction. We show that a properly normalized statistic based on the AH estimating equation, which we call the M statistic, is uniformly convergent and can be inverted to obtain asymptotically valid interval estimates. To further improve the informativeness of our confidence procedure in the unit root and near unit root regions and to alleviate the problem that the AH procedure has greater variation in these regions, we use information from unit root pretesting to select among alternative confidence intervals. Two sequential tests are used to assess how close ρ is to unity, and different intervals are applied depending on whether the test results indicate ρ to be near or far away from unity. When ρ is relatively close to unity, our procedure activates intervals whose width shrinks to zero at a faster rate than that of the confidence interval based on the M statistic. Only when both of our unit root tests reject the null hypothesis does our procedure turn to the M statistic interval, whose width has the optimal N − 1 / 2 T − 1 / 2 rate of shrinkage when the underlying process is stable. Our asymptotic analysis shows this pretest-based confidence procedure to have coverage probability that is at least the nominal level in large samples uniformly over the parameter space. Simulations confirm that the proposed interval estimation methods perform well in finite samples and are easy to implement in practice. A supplement to the paper provides an extensive set of new results on the asymptotic behavior of panel IV estimators in weak instrument settings.

  PublisherOA PDFDOI

• Uniform Inference in Panel Autoregression

  University Libraries (University of Maryland) · 2019-01-01

  preprintOpen access1st authorCorresponding

  This paper considers estimation and inference concerning the autoregressive coefficient (𝜌) in a panel autoregression for which the degree of persistence in the time dimension is unknown. Our main objective is to construct confidence intervals for 𝜌 that are asymptotically valid, having asymptotic coverage probability at least that of the nominal level uniformly over the parameter space. The starting point for our confidence procedure is the estimating equation of the Anderson–Hsiao (AH) IV procedure. It is well known that the AH IV estimation suffers from weak instrumentation when 𝜌 is near unity. But it is not so well known that AH IV estimation is still consistent when 𝜌=1. In fact, the AH estimating equation is very well-centered and is an unbiased estimating equation in the sense of Durbin (1960), a feature that is especially useful in confidence interval construction. We show that a properly normalized statistic based on the AH estimating equation, which we call the 𝕄 statistic, is uniformly convergent and can be inverted to obtain asymptotically valid interval estimates. To further improve the informativeness of our confidence procedure in the unit root and near unit root regions and to alleviate the problem that the AH procedure has greater variation in these regions, we use information from unit root pretesting to select among alternative confidence intervals. Two sequential tests are used to assess how close 𝜌 is to unity, and different intervals are applied depending on whether the test results indicate 𝜌 to be near or far away from unity. When 𝜌 is relatively close to unity, our procedure activates intervals whose width shrinks to zero at a faster rate than that of the confidence interval based on the 𝕄 statistic. Only when both of our unit root tests reject the null hypothesis does our procedure turn to the 𝕄 statistic interval, whose width has the optimal 𝑁−1/2𝑇−1/2 rate of shrinkage when the underlying process is stable. Our asymptotic analysis shows this pretest-based confidence procedure to have coverage probability that is at least the nominal level in large samples uniformly over the parameter space. Simulations confirm that the proposed interval estimation methods perform well in finite samples and are easy to implement in practice. A supplement to the paper provides an extensive set of new results on the asymptotic behavior of panel IV estimators in weak instrument settings.

  PublisherOA PDFDOI

Frequent coauthors

• Norman R. Swanson

  59 shared

• Whitney K. Newey

  31 shared

• Jerry A. Hausman

  National Bureau of Economic Research

  30 shared

• Tiemen Woutersen

  University of Arizona

  27 shared

• Peter C.B. Phillips

  22 shared

• N. Nakagawa

  Iowa State University

  10 shared

• J. C. Moulder

  8 shared

• D. Raulerson

  Whitney Museum of American Art

  7 shared

Education

• Ph.D., Economics

  Yale University

  1994

• Other

  Pennsylvania State University

• Other

  Yale University

• Other

  Shanghai University of Finance and Economics

• Other

  Academia Sinica