# Posts Tagged ‘ heteroskedasticity ’

## Standard, Robust, and Clustered Standard Errors Computed in R

June 15, 2012
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$Standard, Robust, and Clustered Standard Errors Computed in R$

Where do these come from? Since most statistical packages calculate these estimates automatically, it is not unreasonable to think that many researchers using applied econometrics are unfamiliar with the exact details of their computation. For the purposes of illustration, I am going to estimate different standard errors from a basic linear regression model: , using the

## Instrumental Variables without Traditional Instruments

April 14, 2012
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Typically, regression models in empirical economic research suffer from at least one form of endogeneity bias. The classic example is economic returns to schooling, where researchers want to know how much increased levels of education affect income. Estimation using a simple linear model, regressing income on schooling, alongside a bunch of control variables, will typically

## Hey! I made you some Wiener processes!

September 7, 2011
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Check them out. Here are thirty homoskedastic ones: > homo.wiener for (j in 1:30) {  for (i in 2:length(homo.wiener)) {          homo.wiener for (j in 1:30) {        plot( homo.wiener,           type = "l", col = rgb(.1,....

## Hey! I made you some Wiener processes!

September 7, 2011
By

Check them out. Here are thirty homoskedastic ones: > homo.wiener for (j in 1:30) {  for (i in 2:length(homo.wiener)) {          homo.wiener for (j in 1:30) {        plot( homo.wiener,           type = "l", col = rgb(.1,....