Saiz, Albert; Simonsohn, Uri - Institute for the Study of Labor (IZA) - 2008
, document-frequency, proxy variables
Corresponding author:
Albert Saiz
The Wharton School
University of Pennsylvania … factors: sampling error, measurement error, and violation of the “redundancy-
condition” for proxy variables
(i) Sampling … prerequisite for such
use of proxy-variables is that Cov(X, Y
ˆ
|Y)=0 or equivalently that Cov(ε,X)=0 (Jeffrey M.
Wooldrige, 2001 …