Issues with Hausman-Wu test

[Scott Proctor]

Hi everyone,

I am having issues with running a Hausman-Wu test. The output is as follows:

"hausman fe re

Note: the rank of the differenced variance matrix (8) does not equal the number of
coefficients being tested (9); be sure this is what you expect, or there may be
problems computing the test. Examine the output of your estimators for anything
unexpected and possibly consider scaling your variables so that the coefficients
are on a similar scale.

---- Coefficients ----
| (b) (B) (b-B) sqrt(diag(V_b-V_B))
| fe re Difference S.E.
-------------+----------------------------------------------------------------
Dependency | .0625601 .0869425 -.0243824 .
MilExpGDP | -.1617947 -.0907287 -.071066 .195339
Population | -8.84e-09 3.13e-08 -4.01e-08 3.77e-08
Secondary | -.0252826 -.0201809 -.0051017 .
Unemployment | .0036028 -.009116 .0127187 .0101393
TradeGDP | .0032786 .0063996 -.0031209 .0018899
GDPpc | -3.08e-06 -.0000964 .0000933 .0000417
Inflation | -.0016078 -.0028157 .001208 .
UrbanPop | .2251216 .1224237 .102698 .0358208
------------------------------------------------------------------------------
b = consistent under Ho and Ha; obtained from xtreg
B = inconsistent under Ha, efficient under Ho; obtained from xtreg

Test: Ho: difference in coefficients not systematic

chi2(8) = (b-B)'[(V_b-V_B)^(-1)](b-B)
= 33.87
Prob>chi2 = 0.0000
(V_b-V_B is not positive definite)"

I have already tried different syntaxes, and with sigmamore & sigmaless addition, but these have been to no avail.

Any guidance you could provide on the matter would be gratefully appreciated.

Yours,
Scott

[Carlo Lazzaro]

Scott:
welcome to this forum-
As per this pretty old Stata thread (https://www.stata.com/statalist/arch.../msg00756.html) you may want to replace -hausman- with the user-written command -xtoverid-.
Just type -search xtoverid- from within Stata to spot and install it.
For the future, please use CODE delimiters to post what you typed and what Stata gave you back (see the FAQ for this and other posting-related topics). Thanks.

[Scott Proctor]

Carlo,

Thank you for this guidance, it is very much appreciated.

Kind regards,
Scott