Hello Statalist,

I have a problem with command calculating natural logarithm in Stata that is so confusing:
Code:
gen sal=tn1/ld11
    gen lsal=ln(sal)
    gen lnsal=ln(tn1/ld11)
    br if lsal != lnsal
There are 4,942 of 83,752 observations appear after command "br". They looks identical but when I put them into stochastic frontier model, the results are totally different.

Could some one help me to explain why that happen? Thanks alot!