我用frontier做了多投入单产出的SFA模型，结果如下，求大神帮我解释一下，主要是求解释sigma和gamma这些值

Output from the program FRONTIER (Version 4.1c)

instruction file = Eg1-ins.txt
data file =        eg1-dta.txt

Error Components Frontier (see B&C 1992)
The model is a production function
The dependent variable is not logged

the ols estimates are :
                 coefficient     standard-error    t-ratio
  beta 0        -0.12409691E+03  0.69419688E+02 -0.17876328E+01
  beta 1         0.18921295E-01  0.16503859E-02  0.11464770E+02
  beta 2         0.12259323E-01  0.68438856E-02  0.17912811E+01
  beta 3         0.19301565E+01  0.15433354E+00  0.12506397E+02
  sigma-squared  0.26001912E+06
log likelihood function =  -0.74031739E+03
the estimates after the grid search were :
  beta 0        -0.33563736E+02
  beta 1         0.18921295E-01
  beta 2         0.12259323E-01
  beta 3         0.19301565E+01
  sigma-squared  0.25749294E+06
  gamma          0.50000000E-01
   mu is restricted to be zero
   eta is restricted to be zero


iteration =     0  func evals =     20  llf = -0.74035965E+03
    -0.33563736E+02 0.18921295E-01 0.12259323E-01 0.19301565E+01 0.25749294E+06
     0.50000000E-01
gradient step
iteration =     5  func evals =     61  llf = -0.74035656E+03
    -0.33565442E+02 0.18924044E-01 0.12157316E-01 0.19280581E+01 0.25749294E+06
     0.44823130E-01
iteration =    10  func evals =    201  llf = -0.74034974E+03
    -0.42755876E+02 0.18835363E-01 0.12400030E-01 0.19324735E+01 0.25749294E+06
     0.38504740E-01
iteration =    15  func evals =    331  llf = -0.74033842E+03
    -0.72502035E+02 0.18848667E-01 0.12453541E-01 0.19328660E+01 0.25749293E+06
     0.15096389E-01
iteration =    20  func evals =    459  llf = -0.74033670E+03
    -0.73980367E+02 0.18910696E-01 0.12284104E-01 0.19306328E+01 0.25749293E+06
     0.15191472E-01
iteration =    23  func evals =    492  llf = -0.74033666E+03
    -0.73841226E+02 0.18922109E-01 0.12268565E-01 0.19302096E+01 0.25749293E+06
     0.15495606E-01

the final mle estimates are :
                 coefficient     standard-error    t-ratio
  beta 0        -0.73841226E+02  0.25917443E+03 -0.28490938E+00
  beta 1         0.18922109E-01  0.16319904E-02  0.11594497E+02
  beta 2         0.12268565E-01  0.67665336E-02  0.18131241E+01
  beta 3         0.19302096E+01  0.15188046E+00  0.12708742E+02
  sigma-squared  0.25749293E+06  0.10010976E+01  0.25721062E+06
  gamma          0.15495606E-01  0.15457311E+00  0.10024775E+00
   mu is restricted to be zero
   eta is restricted to be zero
log likelihood function =  -0.74033666E+03
the likelihood value is less than that obtained
using ols! - try again using different starting values
number of iterations =     23
(maximum number of iterations set at :   100)
number of cross-sections =     97
number of time periods =      3
total number of observations =     97
thus there are:    194  obsns not in the panel

covariance matrix :
  0.67171387E+05  0.22695914E-02 -0.93488192E-01 -0.18093044E+01  0.12104794E+02
  0.38623259E+02
  0.22695914E-02  0.26633928E-05 -0.28267972E-05 -0.18254434E-03 -0.14007058E-05
  0.19149475E-05
-0.93488192E-01 -0.28267972E-05  0.45785977E-04 -0.22908896E-03 -0.70052844E-05
  0.19717756E-04
-0.18093044E+01 -0.18254434E-03 -0.22908896E-03  0.23067674E-01 -0.28056389E-03
  0.11573969E-03
  0.12104794E+02 -0.14007058E-05 -0.70052844E-05 -0.28056389E-03  0.10021964E+01
  0.68225648E-02
  0.38623259E+02  0.19149475E-05  0.19717756E-04  0.11573969E-03  0.68225648E-02
  0.23892847E-01