Dear statalists:

I want to use prodest to estimate TFP,but my production function is a translog-form,as the following equation showing:
lny=w+a*lnl+b*lnk+(lnl)^2+c*(lnk)^2+d*lnl*lnk
The code is as fllowing,I have found that tfp calculated by prodest+acf+translog is totally different from tfp calculated by prodest+acf,the former tfp is really too big.I wonder if you can figure mistakes in my code.

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Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
insheet using "https://raw.githubusercontent.com/GabrieleRovigatti/prodest/master/stata/data/prodest.csv", names clear

prodest log_y, method(lp) free(log_lab1 log_lab2) proxy(log_materials) state(log_k) valueadded acf translog id(id) t(year) reps
> (50)
.........10.........20.........30.........40.........50


lp productivity estimator                       translog PF
ACF corrected
Dependent variable: value added                 Number of obs      =      2544
Group variable (id): id                         Number of groups   =       497
Time variable (t): year
                                                Obs per group: min =         1
                                                               avg =       5.1
                                                               max =        11

------------------------------------------------------------------------------
       log_y |      Coef.   Std. Err.      z    P>|z|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
    log_lab1 |    .887048   .0024949   355.54   0.000     .8821581    .8919379
    log_lab2 |   .7611732   .0016125   472.05   0.000     .7580128    .7643337
       log_k |  -.5397494   .0018904  -285.52   0.000    -.5434546   -.5360443
     var_1_1 |   .1001688   .0032244    31.07   0.000     .0938492    .1064885
     var_1_2 |   .0163688   .0024564     6.66   0.000     .0115544    .0211832
     var_1_3 |  -.0623013   .0015516   -40.15   0.000    -.0653424   -.0592602
     var_2_2 |   .0797299    .002452    32.52   0.000     .0749241    .0845357
     var_2_3 |  -.0491968   .0015186   -32.40   0.000    -.0521732   -.0462204
     var_3_3 |   .0410398   .0020477    20.04   0.000     .0370265    .0450532
------------------------------------------------------------------------------
Wald test on Constant returns to scale: Chi2 = 4205.71
                                          p = (0.00)
Estimated parameters displayed. To see estimated input elasticities, type predict, parameters

. predict tfp_translog,residual

. prodest log_y, method(lp) free(log_lab1 log_lab2) proxy(log_materials) state(log_k) valueadded acf id(id) t(year) reps(50)
.........10.........20.........30.........40.........50


lp productivity estimator                       Cobb-Douglas PF
ACF corrected
Dependent variable: value added                 Number of obs      =      2544
Group variable (id): id                         Number of groups   =       497
Time variable (t): year
                                                Obs per group: min =         1
                                                               avg =       5.1
                                                               max =        11

------------------------------------------------------------------------------
       log_y |      Coef.   Std. Err.      z    P>|z|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
    log_lab1 |   .5486727   .0662128     8.29   0.000      .418898    .6784474
    log_lab2 |   .4122355   .1238101     3.33   0.001     .1695721    .6548989
       log_k |   .4765666   .0766743     6.22   0.000     .3262877    .6268455
------------------------------------------------------------------------------
Wald test on Constant returns to scale: Chi2 = 43.36
                                          p = (0.00)

. predict tfp_acf,residual

. 
. ****the tfp calculated by prodest+acf+translog is too big,I wonder if you can tell me causes.
. su tfp_translog tfp_acf

    Variable |        Obs        Mean    Std. Dev.       Min        Max
-------------+---------------------------------------------------------
tfp_translog |      2,544     16.4528    1.713113    9.93541   24.53713
     tfp_acf |      2,544    5.779031    .8841653    2.97516   9.391429


end
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