Im using stata 12
and I have a result like this

Code:
. hausman fe re

                 ---- Coefficients ----
             |      (b)          (B)            (b-B)     sqrt(diag(V_b-V_B))
             |       fe           re         Difference          S.E.
-------------+----------------------------------------------------------------
        a |   -.0129722    -.0151672         .002195               .
        b|   -.1919074    -.0865705       -.1053369        .0203032
         c |     .026702      19.1174        -19.0907        3.851953
        d |   -.3443036    -.4121315         .067828               .
why the variable a and d dont have the sqrt ?