# instrumental variable

1. ### Endogenous variable vs instrumental variable

Hi, I've to make a presentation on research methods that happens to include endogenous and instrumental variable. Now, they are not seeming very similar to me, but still I'm failing to draw a clear line and afraid of confusing the two. Can someone kindly explain the differences and similiraries...
2. ### Replacing regressor instead of 2SLS

Hi, can someone explain me why it is usual to run a 2SLS if we are not "satisfied" with one variable and using an instrumental variable to adjust the model? (I am just talking about the just-identified case) Wouldn't it be easier just to replace the variable with the new one, so we have a new...
3. ### Economics - Instrumental Variable: Does including past values of regressors into the IV cause exogeneity assumption to fail?

Setup: Annual panel of 125 countries. I am interested in the effect of x on y. As an instrument z I use an interaction of the variables gamma and delta. gamma fulfils the conditions of relevance and exogeneity. delta is the country’s propensity to receive x, which is an indicator variable based...
4. ### predictor and instrument in IV

I have data about a certain trait X for a small sample of countries and I'm interested in the relationship of X on income per capita Y. I also have a strong predictor Z of X. I have data of Z for a large number of countries so I used it to predict X for all the countries then I regressed Y on...
5. ### Derive Sargan Statistics for 2SLS

Hello. I am trying to show that the Sargan statistics of a classical linear 2SLS estimation can be expressed as the form nR^2, assuming homoscedasticity. I start with the original form of Sargan statistics: S=N x (e’Pz e)/(e’e) Where n is the sample size, Pz= Z(Z’Z)^-1Z’ and Z is the nxL...
6. ### cloglog with endogenous regressors

Howdy! I need to know how one can go about instrumenting endogenous regressors in a cloglog estimation in Stata. I don't see any cloglog options that look like they could do this. Many thanks.
7. ### Binary outcome in instrumental variable analysis

I'm looking to perform an instrumental variable analysis using the following variables: I. a continuous endogenous variable (exposure levels) II. a continuous instrument variable for (I.) III. two exogenous variables (one binary, one continuous) IV. a binary outcome (outcome y/n). However with...
8. ### Use of different outputs in a meta-analysis?

I'm interested in performing a meta-analysis of instrumental variable analyses from a handful of different studies, asking for the same set of model results from all study investigators. As my access is limited to summarized data, i'd like the study investigators to send their ivregress output...