# Tag Info

### How to correct selection bias in an econometric analysis?

As the other answer mentioned, if the Diff-in-diff assumptions hold, it should not be a problem. However, if you think selection might be invalidating your diff-in-diff assumptions, you have two ...
• 5,914

### How to correct selection bias in an econometric analysis?

The parallel trends assumption of Diff-in-diff is essentially an assumption that there is no selection bias. If you are curious about the parallel trends assumption, I encourage you to ask about it in ...
• 3,142
1 vote

### Confusing in explanation of results of t-test

(1) Why they noted like that? I saw all variables changed statistically significant after event Statistically significant change might not be meaningful (or in their lingo pronounced). For example, ...
• 50.1k
1 vote

### Fixed effects vs first difference

Although this conversation is already a bit dated, I want to add a clarification for anyone reading this: FE and FD both effectively use the same amount of information. It can even be shown that a FD-...
1 vote
Accepted

### Assumptions of Logistic Regression Cathegorical predictors only

You do not have to check the assumption of linearity when using categorical predictors, because the notion of linearity is not defined for them. We can define linearity such as $y=a+bx$ for a pair of ...
• 2,131
Accepted

### Results Chi square test vs binomial logit

I just did this myself and got totally different results from you. ...
• 365

### IV Regression with More Observations for First Stage than Second Stage

You should completely omit the observations with missing data. The explanation takes a few lines, but the key fact of the first stage regression is that predicted values are uncorrelated with ...
• 3,142

### When should I NOT control for unit-fixed effects?

It is always a good default to include individual fixed effects. If you believe that omitting the individual fixed effect would not induce bias, then you can perform random effects estimation and ...
• 3,142
1 vote

### Is it possible to integrate propensity score (weighting or matching) and synthetic control method?

You can't integrate the two because there is nothing to integrate. Both approaches are solving similar problems (getting the right counterfactual for causal comparisons) in similar ways (applying ...
• 5,914
1 vote

### The definition of control variables

The professor's notation is a little non-standard, but in English, your professor's math is saying "conditional on $X$, the error, $U$ is mean-independent of $D$." Thus, if we control for $X$...
• 3,142

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