Questions tagged [instrumental-variable]

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Is 2SLS asymptotically MLE?

$$y_i =\beta_0 +\beta_1 x_{1i}+\beta_2 x_{2i}+\varepsilon_i$$ Suppose $x_1$ is endogenous but $x_2$ is exogenous. We have two excluded instruments, $z_1$ and $z_2$. The first stage is: $$x_{1i} =\...
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Instrumental Variables - Exogeneity Tests using region characteristics

I am using IV methods to establish the causality, I want to run some exogeniety tests. I have been going over Woolridge (Econometric Analysis of Cross Section and Panel Data, 2010) and I am not ...
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Estimating parameters when introducing IV Instrument

Say, you have a model $$ y_{it} = \beta_1 a_{it} + \beta_2 b_{it} $$ And you find that $a_{it}$ is endogenous, therefore, you need to find an instrument for it. Say you find an instrument $z_{it} = \...
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1 vote
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Fuzzy RDD when individuals can affect the probability of treatment

I want to evaluate the effect of getting into a program on earnings. In my case individuals that get a score above $c$ can decide weather to get into the program or not. On the other hand those that ...
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3 votes
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IV regression: first stage in logs, second stage in levels?

I have a regression in levels, derived from theory. I want to instrument one of the variables, but the best instrument I find has a weak correlation to the endogenous variable in levels, and a strong ...
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Can current value of left hand side of a simultaneous equation be an instrument?

Inflation and output gap are endogenous variables in this regression. Can $r_t$ be an instrument? I know the lags can, but it is the first time I am seeing the current value of the left-hand side ...
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5 votes
1 answer
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C-statistic when one estimation is just identified

My question is motivated by Do, Joshi, and Stopler's paper "Can Environmental Policy Reduce Infant Mortality? Evidence from the Ganga Pollution Cases". A simplified form of their models that ...
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3 votes
0 answers
119 views

Kleibergen Paap F-statistic

I have commonly seen references to a Kleibergen and Paap F-statistic. In their paper, I see a derivation of a chi-squared statistic, but don't see any references to the F-distribution or F-stat. In ...
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2 votes
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92 views

Difference between AR confidence intervals reported in weakiv versus twostepweakiv

Should the Anderson-Rubin confidence intervals reported in weakiv and twostepweakiv be equal to each other? Sun (2018) does not ...
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1 answer
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IV estimate for entire sample is larger than IV estimates for subsets of sample?

I am using two-stage least squares to estimate a local average treatment effect, with 'treatment' being the endogenous variable and 'assignment to treatment' being the instrument. If I use my full ...
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Advice on research methodology

I had wanted to ask this community for some advice on some potential methodologies I am developing. Context: I want to evaluate the effectiveness of a component of this scholarship program, which ...
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1 answer
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Is exogeneity guaranteed for a lottery-generated instrumental variable?

If using $z$ as an instrument for $x$, to study the effect $x$ has on $y$ and given that $z$ was indeed generated through a lottery, is it definite that exogeneity of $z$ will hold? I have looked at ...
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How should I regress income inequality on economic growth?

I would like to know which variables to use to regress income inequality on economic growth. For income inequality, I am thinking of using the Gini index, but don't know what measurement exactly. For ...
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2 votes
1 answer
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Interacting covariates with the instrument in the first stage

If I want to run a 2 stage least squares (2SLS) regression with: Relationship of interest: $Y = \alpha + \beta X + \varepsilon $, where $X$ is the endogenous explanatory variable of interest. If I ...
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2 votes
1 answer
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Why do we need at least as many instrumental variables as endogenous regressors to identify parameters in 2SLS?

As the title says. Why do we need at least as many instrumental variables as endogenous regressors to identify parameters?
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Instrumental variable regression: How many interpretations?

I was reading Amemiya "Non-linear regression models" (1983) in which he says that This statement should not be construed as a criticism of Theil's interpretation. I know of at least six ...
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1 answer
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The instrument in "The Colonial Origins of Comparative Development"

I am hoping to understand when an instrument is appropriate. For the purposes of this question, I'm considering a simplied version of the model in AJR (2000): $$\begin{aligned}\text{GDP} &\sim \...
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1 vote
1 answer
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Using dependent variable's and exogenous variables' lags as instruments in 2SLS

Suppose we have the following structural equations: $$y=\beta_0+\beta_1x+\beta_2z_z+\beta_3z_3+\epsilon,$$ where $x$ is the endogenous variable and $z_1,z_2$ are exogenous variables. In the literature,...
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How to calculate and interpret a marginal treatment effect (local instrumental variable)? (Intuition through simple example.)

I am working on the intuition behind local instrumental variables (LIV), also known as the marginal treatment effect (MTE). I have worked some time on this and would benefit from solving a simple. I ...
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2 votes
2 answers
177 views

What does it mean if the controls in my IV model are correlated with my instrument?

I am seeking to understand what it means for my 2SLS IV model if my controls are correlated with my instrument (such that when I add additional controls to my model that are positively correlated with ...
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1 vote
0 answers
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Stata's "ivregress 2sls" command - generating F-stats to test for weak instrument

I am transitioning to using the "ivregress 2sls" command in Stata for IV estimates. I've been trying to produce F-statistics to test for whether the instrument is weak. I believe that the ...
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4 votes
1 answer
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Skepticism about the claims of instrument variable validity/exclusion through a statistical test—the Arellano-Bond Test

I am an applied researcher and occasionally come across papers that have panel data and that use dynamic models with both a fixed-effects term and lagged DV (or multiple autoregressive terms): $y_{it} ...
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4 votes
2 answers
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is endogeneity a problem in the first-stage regression in a two-stage least square regression?

We have this model: $$D=\alpha_1+\gamma_1 Z + \epsilon_1$$ $$Y=\alpha_2+\gamma_2 D + \epsilon_2$$ Notations are as usual: Y is the outcome, D is the treatment, Z is the instrument Two conditions for ...
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1 answer
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Why are my 2SLS estimates much larger than my OLS estimates?

When performing IV regression, it is often taken as a sign of unbiasedness if the IV estimates are similar to the OLS estimates of the same model. My question is: If the estimates are very different,...
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1 vote
0 answers
36 views

Weak Instrument - Stock and Yogo

I have the following structural equations where $G,Z$ are endogenous and $X,Y$ are exogenous $$ G_d=B_0+B_1Z+B_2X+u_1\\ G_s=a_0 +a_1Z+a_2Y+u_2 \\ G_d=G_s $$ Now, I would like to perform 2SLS, thus, ...
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3 votes
2 answers
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Some confusions about instrumental variable (econometrics)

As the title says, I have some confusions about instrumental variable. According to my lecture note (which is supposed to be reliable), instrumental variable has two big properties: Validity: an ...
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0 votes
1 answer
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Is it reasonable, in panel data, to use past values of explanatory variables as instruments to deal with simultaneous causality?

I am trying to examine the determinants of economic growth, essentially regressing a number of variables upon economic growth. I face a problem that there is likely simultaneous causality between many ...
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1 vote
1 answer
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Testing for weak instrument

I have 3 endogenous variables in my model and I have identified 3 (or max 4) instruments. I wanted to know appropriate test for identifying whether the instruments are weak or not given that I have ...
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instrumental variables

I have a question related to IV methods. Suppose I have a regression $Y = a + b_1 X_1 + b_2 X_2 + \epsilon$, where $Y$ is a dependent variable and $X_1$ is an endogenous independent variable and $...
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3 votes
1 answer
58 views

Imbens and Angrist (1994): the $D_i(z)$ variables

I'm referring to the Econometrica (1994) paper by Imbens and Angrist. In particular, I don't really understand the random variables $D_i(z)$ (defined on page 468). Could you please provide me with ...
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2 votes
1 answer
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Validity condition for Instrumental Variables

My professor states the validity condition in the following way: $W$ (the matrix of instrumental variables) must be such that $ \text{plim} \, \frac{W'u}{N}=0$, where $u$ is the error term. ...
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5 votes
1 answer
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Confounding versus endogenous variables. What is their relative hierarchical position?

There are valuable resources on the lexicon of types of variables quickly accessible, such as here. However, some of these concepts appear side-by-side often enough to make them confusing. For ...
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6 votes
2 answers
272 views

Instrumental Variable Paper for Minimum Wage

I am trying to write a paper dealing with minimum wages and employment. I understand there is simultaneity bias between these two variables so I must come up with an instrument. Does anyone have any ...
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Using an instrument in IV that is not strictly exogenous to the variable it is instrumenting?

I am considering instrumenting HIV with ODA, to evaluate the impact of HIV on gold mining. There is a clear relationship between HIV and ODA, however it may easily be argued this is an endogenous ...
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0 votes
1 answer
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Difference between $x$ and $X$

Sorry for my bad english, i'll try to explain my difficulty. 1° Question In the last exam an exercise asked to derivate OLS estimators and calculate their value with the data provided (ex.: $\sum ...
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2 votes
2 answers
511 views

Testing for Endogeneity

I apologize if this question is very basic. I have the following plain vanilla Instrumental Variable model. $Y=\alpha+X\beta+\varepsilon$ $X=\delta+Z\gamma+\eta$ $\varepsilon\perp\eta,\quad Z\perp\...
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4 votes
1 answer
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Can you use more than one instrumental variables in an Econometric model?

Can you use two instrumental variables $z_1$ and $z_2$ at the same time for $x_1$ and $x_2$, in the following regression model $y=a+bx_1+cx_2+dX_{other}+e$, where $y$ is the explained variable, $...
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4 votes
1 answer
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Testing if one regressor is a proxy for another

I'm reading Guiso, Sapienza and Zingales: "Trusting the Stock Market" The Journal of Finance, Vol. 63, No. 6, 2008 and have a question about how they test whether trust is a proxy for risk aversion. ...
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1 vote
0 answers
441 views

How to test if variables are jointly determined?

If I wanted to test, for example, if consumption growth and credit growth are jointly determined, and therefore justifying the use of instrumental variables, how would I go about this? Would running a ...
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9 votes
3 answers
23k views

What is the difference between two stage least squares and instrumental variable regression?

I'm doing independent study and I am having trouble understanding the difference between these two estimators. I get that 2SLS is predicting the endogenous variable, and that instrumental variables ...
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0 votes
1 answer
415 views

IV:Quasi-random variance V.S. 'Placebo' check

I read some papers about transportation infrastructure. I am confuse with the following two case. Some routes are unlikely to have been randomly assigned across cities over time. Thus, In some papers(...
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Trouble Deriving Indentification Scheme in Gertler-Karadi (2015) AEJ

I'm having trouble following a derivation that Gertler-Karadi (2015) AEJ http://pubs.aeaweb.org/doi/pdfplus/10.1257/mac.20130329 do in their paper on Footnote 4 on the bottom of page 52. I've tried ...
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7 votes
2 answers
155 views

Using another person's guess as an IV

In Estimates of the Economic Return to Schooling from a New Sample of Twins by Orley Ashenfelter and Alan Krueger, they correct sampling error with an IV. They claim that their results imply a larger ...
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3 votes
2 answers
901 views

How to justify an instrumental variable?

I am hoping for some tips on what I could do for a term paper in applied econometrics. We are running a 2sls where I want to use a firm's location as an IV. How can I go about justifying it is a valid ...
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1 vote
1 answer
433 views

Which regression technique is used for calculating price elasticity in practice

Since we need to consider 'Endogeneity' between price and quantity while calculating price elasticity and since linear regression cannot handle the phenomenon of endogeneity if objective of the model ...
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1 vote
0 answers
127 views

Using an interaction term as the instrument (as in Barro QJE (2011))

I recently came across Barro and Redlick QJE (2011) paper, "Macroeconomic Effects from Government Purchases and Taxes", in which the authors instrument for defense spending with an interaction term ...
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7 votes
2 answers
1k views

Best instruments for "years of schooling"/"education"

As an answer to question “Seminal papers that later were proven to contain errors”, @snoram mentioned Angrist and Krueger (1991), and there use of quarter of birth as an (exogenous) instrument for ...
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5 votes
1 answer
173 views

IV - Is this procedure valid?

I have three variables: $y$, $x_1$ and $z$. I'm interested in finding the effect of $x_1$ on $y$. Unfortunately $x_1$ is endogenous so I use an instrument z. I know that $z$ is correlated with $x_1$....
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