[Limdep Nlogit List] efficiency scores above 1

[dgiantsios at uom.gr]

Hi All,
I estimated cost efficiency for Battesse-Coelli (1995) model with panel
data. I added the comand Costeff=....; with the List; and i had the
following results:

Data listing for stochastic frontier model
Observ Pd. Data row  Observed Y     Fitted Y      Y - Xb      E[u|e]
     1   1        1     12.6523       8.0012      4.6511      4.6912
     1   2        2     12.2788       7.6433      4.6355      4.6507
     1   3        3     12.6505       7.7804      4.8700      4.6105
     1   4        4     12.5984       7.8458      4.7526      4.5707
     1   5        5     13.4217       8.5396      4.8821      4.5312
     1   6        6     13.7691       9.1428      4.6263      4.4920
     1   7        7     13.0413       8.9292      4.1121      4.4532
     1   8        8     12.8631       8.6091      4.2540      4.4147
     2   1       10     12.0794       7.2354      4.8441      4.6294
     2   2       11     12.5092       7.8969      4.6123      4.5894
     2   3       12     12.6131       8.2284      4.3847      4.5497
     2   4       13     13.7244       9.4242      4.3002      4.5104
     2   5       14     13.3188       9.0529      4.2659      4.4714
     2   6       15     13.2917       8.6882      4.6035      4.4328
     2   7       16     13.2386       8.7104      4.5282      4.3945
     2   8       17     13.2547       8.6791      4.5757      4.3565
     3   1       19     10.4277       5.5600      4.8677      4.5799
     3   2       20     10.9968       6.3027      4.6941      4.5403
     3   3       21     11.1416       6.8385      4.3031      4.5011
     3   4       22     12.2998       8.1706      4.1291      4.4622
     3   5       23     12.2120       7.9780      4.2341      4.4236
     3   6       24     12.1462       7.7386      4.4077      4.3854
     3   7       25     12.2588       7.8629      4.3959      4.3475
     3   8       26     12.4791       7.8318      4.6472      4.3099
     4   1       28     11.0053       6.3753      4.6300      4.5413
     4   2       29     11.9644       7.4316      4.5327      4.5021
     4   3       30     12.3282       7.9215      4.4067      4.4632
     4   4       31     13.6965       9.5069      4.1896      4.4246
     4   5       32     13.4434       9.1795      4.2639      4.3864
     4   6       33     13.3726       8.9541      4.4185      4.3485
     4   7       34     13.4541       9.0695      4.3846      4.3109
     4   8       35     13.5175       8.9951      4.5224      4.2736
     5   1       37     10.4945       4.2519      6.2426      4.6274
     5   2       38     10.0848       4.9867      5.0981      4.5874
     5   3       39     13.0467       8.7164      4.3303      4.5477
     5   4       40     11.7206       7.5400      4.1806      4.5084
     5   5       41     12.4345       8.2190      4.2155      4.4695
     5   6       42     12.7461       8.8359      3.9101      4.4308
     5   7       43     12.9505       8.8448      4.1057      4.3925
     5   8       44     12.8575       8.8661      3.9914      4.3546
Does somebody know why the column E[u/e] give efficiency estimates largely
above 1??? The theory states that efficiency scores must take values
between 0 and 1.

Best Regards
Dimitrios Giantsios
Phd Candidate