Dear all,
I am estimating 'xthtaylor" with bootstrap standard error.
xthtaylor depvar indepvars, endog(vars) vce(boot)
Stata10 gives estimation results with the following notation.
Bootstrap replications (50)
----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5
.....xx....x..xx.x......x.x........xx.x...x....x.. 50
However, Stata11 cannot estimate the model. It says:
o. operator not allowed
an error occurred when bootstrap executed xthtaylor
r(101);
http://www.stata.com/support/faqs/lang/post.html says:
"As of Stata 11, variables are no longer dropped because of collinearity.
Instead, these variables are omitted and are labeled with the "o." operator
in the column names of the resulting parameter vector."
My questions are:
1. What does "xx...x..xx" mean in Stata10?
2. Why can't Stata11 estimate the model with the same code?
3. What is the difference between "dropping" and "omitting" a variable due
to collinearity?
Thank you for your help in advance.
Mike.
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