On the Asymptotic Size of Subvector Tests in the Linear Instrumental Variables Model

2011 ◽  
Author(s):  
Patrik Guggenberger
Keyword(s):  
Instrumental Variables ◽  
Asymptotic Size

ON THE ASYMPTOTIC SIZE DISTORTION OF TESTS WHEN INSTRUMENTS LOCALLY VIOLATE THE EXOGENEITY ASSUMPTION

2011 ◽  
Vol 28 (2) ◽  
pp. 387-421 ◽  
Author(s):  
Patrik Guggenberger
Keyword(s):  
Instrumental Variables ◽  
Alternative Measure ◽  
Inference Procedure ◽  
Size Distortion ◽  
Weak Instruments ◽  
Testing Procedures ◽  
Generalized Empirical Likelihood ◽  
Asymptotic Size ◽  
Nominal Size ◽  
Distortion Reduction

In the linear instrumental variables model with possibly weak instruments we derive the asymptotic size of testing procedures when instruments locally violate the exogeneity assumption. We study the tests by Anderson and Rubin (1949, The Annals of Mathematical Statistics 20, 46–63), Moreira (2003, Econometrica 71, 1027–1048), and Kleibergen (2005, Econometrica 73, 1103–1123) and their generalized empirical likelihood versions. These tests have asymptotic size equal to nominal size when the instruments are exogenous but are size distorted otherwise. While in just-identified models all the tests that we consider are equally size-distorted asymptotically, the Anderson-Rubin type tests are less size-distorted than the tests of Moreira (2003) and Kleibergen in over-identified situations. On the other hand, we also show that there are parameter sequences under which the former test asymptotically overrejects more frequently. Given that strict exogeneity of instruments is often a questionable assumption, our findings should be important to applied researchers who are concerned about the degree of size distortion of their inference procedure. We suggest robustness of asymptotic size under local model violations as a new alternative measure to choose among competing testing procedures. We also investigate the subsampling and hybrid tests introduced in Andrews and Guggenberger (2010a, Journal of Econometrics 158, 285–305) and show that they do not offer any improvement in terms of size-distortion reduction over the Anderson-Rubin type tests.

Analysis of Communication-to-Computation Based on Asymptotic Size for Iterative Methods

2014 ◽  
Vol 36 (4) ◽  
pp. 782-789
Author(s):  
Xiao-Wen XU ◽  
Ze-Yao MO ◽  
Lin-Ping WU
Keyword(s):  
Iterative Methods ◽  
Asymptotic Size

scholarly journals Optimizing Transmit Sequence and Instrumental Variables Receiver for Dual-Function Complexity System

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yu Yao ◽  
Junhui Zhao ◽  
Lenan Wu
Keyword(s):  
Approximate Solution ◽  
Instrumental Variables ◽  
Performance Index ◽  
Dual Function ◽  
Np Hard ◽  
Match Filter ◽  
Filter Output ◽  
Phase Code ◽  
Discrete Phase ◽  
Simulation Results

This correspondence deals with the joint cognitive design of transmit coded sequences and instrumental variables (IV) receive filter to enhance the performance of a dual-function radar-communication (DFRC) system in the presence of clutter disturbance. The IV receiver can reject clutter more efficiently than the match filter. The signal-to-clutter-and-noise ratio (SCNR) of the IV filter output is viewed as the performance index of the complexity system. We focus on phase only sequences, sharing both a continuous and a discrete phase code and develop optimization algorithms to achieve reasonable pairs of transmit coded sequences and IV receiver that fine approximate the behavior of the optimum SCNR. All iterations involve the solution of NP-hard quadratic fractional problems. The relaxation plus randomization technique is used to find an approximate solution. The complexity, corresponding to the operation of the proposed algorithms, depends on the number of acceptable iterations along with on and the complexity involved in all iterations. Simulation results are offered to evaluate the performance generated by the proposed scheme.

Does Board Independence Increase Firm Value? Evidence from Closed-End Funds

2019 ◽  
pp. 1-24
Author(s):  
Matthew E. Souther
Keyword(s):  
Instrumental Variables ◽  
Firm Value ◽  
Board Independence ◽  
Difference In Differences ◽  
Cross Sectional ◽  
Closed End Funds ◽  
The Impact ◽  
New Evidence

Researchers disagree about the impact of board independence on firm value. The disagreement generally stems from the endogenous nature of board appointments. I add new evidence to this discussion by using a sample of closed-end funds to document the value-enhancing effects of independent boards. Using cross-sectional, difference-in-differences, and instrumental variables techniques, I address these endogeneity concerns and find consistent evidence that board independence is associated with higher firm value.

The determinants of the intensity of home-based informal care among cancer patients in receipt of home-based palliative care

2020 ◽  
pp. 026921632097927
Author(s):  
Jiaoli Cai ◽  
Li Zhang ◽  
Denise Guerriere ◽  
Peter C Coyte
Keyword(s):  
Palliative Care ◽  
Marital Status ◽  
Cancer Patients ◽  
Informal Care ◽  
Instrumental Variables ◽  
Spousal Caregivers ◽  
Living Alone ◽  
Policy Makers ◽  
Cohort Design ◽  
Home Based

Background: Understanding the determinants of the intensity of informal care may assist policy makers in the identification of supports for informal caregivers. Little is known about the utilization of informal care throughout the palliative care trajectory. Aim: The purpose of this study was to analyze the intensity and determinants of the use of informal care among cancer patients over the palliative care trajectory. Design: This was a longitudinal, prospective cohort design conducted in Canada. Regression analysis using instrumental variables was applied. Setting/participants: From November 2013 to August 2017, a total of 273 caregivers of cancer patients were interviewed biweekly over the course of the care recipient’s palliative care trajectory. The outcome was the number of hours of informal care provided by unpaid caregivers, that is, hours of informal care. Results: The number of hours of informal care increased as patients approached death. Home-based nursing care complemented, and hence, increased the provision of informal care. Patients living alone and caregivers who were employed were associated with the provision of fewer hours of informal care. Spousal caregivers provided more hours of informal care. Patient’s age, sex, and marital status, and caregiver’s age, sex, marital status, and education were associated with the number of hours of informal care. Conclusions: The intensity of informal care was determined by predisposing, enabling, and needs-based factors. This study provides a reference for the planning and targeting of supports for the provision of informal care.

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