2
$\begingroup$

When using did_imputation (a Difference-in-Difference approach following Borusyak, 2021), I faced this problem

Could not run imputation for some observations because some absorbed variables/FEs are collinear in the D==0 subsample (the control subsample) but not in the full sample Please note that autosample does not know how to deal with this. Please correct the sample manually equation/system not identified

I am wondering what is the problem of this situation intuitively? And what I should deal with this problem?

In specific, I want to control industry*year fixed effects. When I control for SIC2 industry classification * year fixed effect, this problem does not exist. But when I control for SIC3 industry classification * year fixed effect, this problem happens. Is it the justification for me to use SIC2 instead SIC3 in my research?

Below is my SIC2 summary,I have 20 years in my sample.

INDC3   Freq.     Percent   Cum.
        
AUTMB   7,041        3.20   3.20
BRESR   17,500        7.95  11.15
CHMCL   10,752        4.89  16.04
CNSTM   20,695        9.40  25.44
CONPS   19,742        8.97  34.41
ENEGY   8,311        3.78   38.18
FDBEV   18,093        8.22  46.40
HLTHC   9,528        4.33   50.73
INDGS   48,891       22.21  72.95
MEDIA   5,946        2.70   75.65
PCDGS   5,014        2.28   77.93
RTAIL   10,855        4.93  82.86
TECNO   22,221       10.10  92.95
TELCM   7,348        3.34   96.29
TRLES   8,159        3.71   100.00
        
Total   220,096      100.00

This is my SIC3 summary

SIC3        Freq.     Percent   Cum.
            
    100 5        0.00   0.00
    101 278        0.11 0.11
    102 515        0.20 0.30
    103 444        0.17 0.47
    104 938        0.36 0.83
    106 6        0.00   0.83
    108 189        0.07 0.90
    109 547        0.21 1.11
    110 21        0.01  1.12
    111 22        0.01  1.13
    112 53        0.02  1.15
    115 89        0.03  1.18
    116 3        0.00   1.18
    119 362        0.14 1.32
    122 202        0.08 1.40
    123 85        0.03  1.43
    124 198        0.08 1.50
    131 451        0.17 1.68
    132 476        0.18 1.86
    133 82        0.03  1.89
    134 39        0.01  1.90
    138 1,231        0.47   2.37
    139 242        0.09 2.46
    141 130        0.05 2.51
    142 510        0.19 2.71
    144 206        0.08 2.78
    145 182        0.07 2.85
    147 176        0.07 2.92
    148 39        0.01  2.93
    149 141        0.05 2.99
    152 283        0.11 3.10
    153 2,732        1.04   4.13
    154 3,734        1.42   5.55
    160 1        0.00   5.55
    161 1,691        0.64   6.20
    162 3,294        1.25   7.45
    171 539        0.20 7.65
    172 169        0.06 7.72
    173 711        0.27 7.99
    174 165        0.06 8.05
    175 87        0.03  8.08
    176 75        0.03  8.11
    177 190        0.07 8.18
    179 1,763        0.67   8.85
    180 3        0.00   8.86
    181 130        0.05 8.90
    182 19        0.01  8.91
    201 961        0.37 9.28
    202 1,332        0.51   9.78
    203 1,686        0.64   10.42
    204 1,363        0.52   10.94
    205 539        0.20 11.15
    206 902        0.34 11.49
    207 734        0.28 11.77
    208 1,790        0.68   12.45
    209 2,918        1.11   13.56
    211 145        0.06 13.61
    212 141        0.05 13.67
    213 252        0.10 13.76
    214 47        0.02  13.78
    219 11        0.00  13.78
    221 578        0.22 14.00
    222 22        0.01  14.01
    223 41        0.02  14.03
    224 229        0.09 14.12
    225 693        0.26 14.38
    226 703        0.27 14.65
    227 177        0.07 14.71
    228 870        0.33 15.04
    229 376        0.14 15.19
    231 157        0.06 15.25
    232 1,247        0.47   15.72
    233 1,191        0.45   16.17
    234 288        0.11 16.28
    235 103        0.04 16.32
    236 198        0.08 16.40
    237 54        0.02  16.42
    238 487        0.19 16.60
    239 1,029        0.39   16.99
    241 270        0.10 17.10
    242 310        0.12 17.21
    243 1,008        0.38   17.60
    244 16        0.01  17.60
    245 118        0.04 17.65
    249 601        0.23 17.88
    251 1,158        0.44   18.32
    252 607        0.23 18.55
    253 70        0.03  18.57
    254 353        0.13 18.71
    259 324        0.12 18.83
    260 7        0.00   18.83
    261 243        0.09 18.93
    262 452        0.17 19.10
    263 476        0.18 19.28
    265 710        0.27 19.55
    267 2,597        0.99   20.54
    271 286        0.11 20.64
    272 523        0.20 20.84
    273 1,033        0.39   21.24
    274 545        0.21 21.44
    275 1,201        0.46   21.90
    276 98        0.04  21.94
    277 15        0.01  21.94
    278 142        0.05 22.00
    279 152        0.06 22.05
    281 2,284        0.87   22.92
    282 2,454        0.93   23.85
    283 2,260        0.86   24.71
    284 1,590        0.60   25.32
    285 432        0.16 25.48
    286 2,608        0.99   26.47
    287 1,190        0.45   26.93
    289 2,090        0.79   27.72
    290 1        0.00   27.72
    291 264        0.10 27.82
    295 315        0.12 27.94
    299 550        0.21 28.15
    301 34        0.01  28.16
    302 220        0.08 28.25
    305 287        0.11 28.36
    306 714        0.27 28.63
    308 3,153        1.20   29.82
    311 57        0.02  29.85
    314 971        0.37 30.22
    315 10        0.00  30.22
    316 30        0.01  30.23
    317 215        0.08 30.31
    319 61        0.02  30.34
    320 7        0.00   30.34
    321 111        0.04 30.38
    322 563        0.21 30.59
    323 180        0.07 30.66
    324 228        0.09 30.75
    325 617        0.23 30.98
    326 416        0.16 31.14
    327 1,817        0.69   31.83
    328 88        0.03  31.87
    329 507        0.19 32.06
    331 2,748        1.04   33.10
    332 777        0.30 33.40
    333 358        0.14 33.53
    334 424        0.16 33.70
    335 1,507        0.57   34.27
    336 265        0.10 34.37
    339 73        0.03  34.40
    341 104        0.04 34.44
    342 698        0.27 34.70
    343 608        0.23 34.93
    344 2,124        0.81   35.74
    345 307        0.12 35.86
    346 1,244        0.47   36.33
    347 258        0.10 36.43
    348 204        0.08 36.51
    349 2,799        1.06   37.57
    351 687        0.26 37.83
    352 384        0.15 37.98
    353 1,697        0.64   38.62
    354 2,397        0.91   39.53
    355 2,073        0.79   40.32
    356 2,890        1.10   41.42
    357 2,053        0.78   42.20
    358 1,688        0.64   42.84
    359 717        0.27 43.11
    361 912        0.35 43.46
    362 1,151        0.44   43.90
    363 1,467        0.56   44.45
    364 1,582        0.60   45.06
    365 535        0.20 45.26
    366 3,120        1.19   46.44
    367 5,082        1.93   48.38
    369 2,644        1.00   49.38
    371 2,404        0.91   50.29
    372 787        0.30 50.59
    373 363        0.14 50.73
    374 119        0.05 50.78
    375 198        0.08 50.85
    376 194        0.07 50.93
    379 233        0.09 51.01
    381 722        0.27 51.29
    382 3,585        1.36   52.65
    384 1,995        0.76   53.41
    385 68        0.03  53.44
    386 786        0.30 53.73
    387 103        0.04 53.77
    391 182        0.07 53.84
    393 14        0.01  53.85
    394 453        0.17 54.02
    395 164        0.06 54.08
    396 104        0.04 54.12
    399 561        0.21 54.34
    401 270        0.10 54.44
    411 372        0.14 54.58
    412 181        0.07 54.65
    413 70        0.03  54.67
    414 119        0.05 54.72
    415 6        0.00   54.72
    421 2,122        0.81   55.53
    422 2,115        0.80   56.33
    423 285        0.11 56.44
    431 15        0.01  56.45
    441 592        0.22 56.67
    442 180        0.07 56.74
    444 237        0.09 56.83
    448 229        0.09 56.92
    449 1,015        0.39   57.30
    451 158        0.06 57.36
    452 152        0.06 57.42
    458 344        0.13 57.55
    461 465        0.18 57.73
    472 1,016        0.39   58.11
    473 738        0.28 58.39
    474 6        0.00   58.40
    478 207        0.08 58.48
    481 898        0.34 58.82
    482 29        0.01  58.83
    483 489        0.19 59.01
    484 629        0.24 59.25
    489 700        0.27 59.52
    491 1,580        0.60   60.12
    492 758        0.29 60.41
    493 55        0.02  60.43
    494 111        0.04 60.47
    495 629        0.24 60.71
    496 130        0.05 60.76
    501 1,418        0.54   61.30
    502 548        0.21 61.51
    503 1,612        0.61   62.12
    504 2,410        0.92   63.03
    505 1,251        0.48   63.51
    506 2,139        0.81   64.32
    507 864        0.33 64.65
    508 2,169        0.82   65.48
    509 1,192        0.45   65.93
    511 581        0.22 66.15
    512 1,198        0.46   66.61
    513 1,377        0.52   67.13
    514 2,712        1.03   68.16
    515 493        0.19 68.35
    516 1,312        0.50   68.85
    517 1,154        0.44   69.28
    518 387        0.15 69.43
    519 1,330        0.51   69.94
    521 100        0.04 69.97
    523 57        0.02  70.00
    525 111        0.04 70.04
    526 41        0.02  70.05
    531 200        0.08 70.13
    533 36        0.01  70.14
    539 261        0.10 70.24
    541 531        0.20 70.44
    542 155        0.06 70.50
    543 32        0.01  70.52
    544 25        0.01  70.53
    545 15        0.01  70.53
    546 116        0.04 70.58
    549 289        0.11 70.68
    551 263        0.10 70.78
    552 186        0.07 70.86
    553 41        0.02  70.87
    554 470        0.18 71.05
    555 11        0.00  71.05
    557 101        0.04 71.09
    559 62        0.02  71.12
    560 7        0.00   71.12
    561 275        0.10 71.22
    562 724        0.28 71.50
    563 63        0.02  71.52
    564 486        0.18 71.71
    565 197        0.07 71.78
    566 285        0.11 71.89
    569 571        0.22 72.11
    571 679        0.26 72.37
    572 398        0.15 72.52
    573 779        0.30 72.81
    581 2,111        0.80   73.61
    591 376        0.14 73.76
    592 124        0.05 73.80
    593 32        0.01  73.82
    594 1,305        0.50   74.31
    596 1,033        0.39   74.71
    598 75        0.03  74.73
    599 917        0.35 75.08
    602 58        0.02  75.10
    608 7        0.00   75.11
    609 196        0.07 75.18
    614 220        0.08 75.27
    615 686        0.26 75.53
    616 95        0.04  75.56
    621 155        0.06 75.62
    622 76        0.03  75.65
    623 19        0.01  75.66
    628 608        0.23 75.89
    631 128        0.05 75.94
    632 39        0.01  75.95
    633 203        0.08 76.03
    635 16        0.01  76.04
    636 11        0.00  76.04
    641 803        0.31 76.34
    651 6,426        2.44   78.79
    653 2,078        0.79   79.58
    655 618        0.23 79.81
    671 9,305        3.54   83.35
    672 179        0.07 83.42
    673 7        0.00   83.42
    679 808        0.31 83.73
    701 856        0.33 84.05
    702 71        0.03  84.08
    703 210        0.08 84.16
    711 22        0.01  84.17
    721 316        0.12 84.29
    722 49        0.02  84.30
    723 157        0.06 84.36
    724 97        0.04  84.40
    726 62        0.02  84.42
    729 345        0.13 84.56
    731 1,161        0.44   85.00
    733 299        0.11 85.11
    734 341        0.13 85.24
    735 1,193        0.45   85.69
    736 507        0.19 85.89
    737 14,966        5.69  91.57
    738 3,022        1.15   92.72
    742 47        0.02  92.74
    751 809        0.31 93.05
    752 171        0.06 93.11
    753 705        0.27 93.38
    754 241        0.09 93.47
    762 768        0.29 93.77
    769 1,134        0.43   94.20
    781 784        0.30 94.49
    782 459        0.17 94.67
    783 123        0.05 94.72
    784 128        0.05 94.76
    792 32        0.01  94.78
    793 20        0.01  94.78
    794 238        0.09 94.87
    799 1,319        0.50   95.38
    801 84        0.03  95.41
    802 59        0.02  95.43
    804 76        0.03  95.46
    805 253        0.10 95.55
    806 232        0.09 95.64
    807 182        0.07 95.71
    808 77        0.03  95.74
    809 316        0.12 95.86
    811 107        0.04 95.90
    821 29        0.01  95.91
    822 23        0.01  95.92
    824 494        0.19 96.11
    829 442        0.17 96.28
    831 143        0.05 96.33
    832 33        0.01  96.34
    833 14        0.01  96.35
    835 81        0.03  96.38
    836 116        0.04 96.42
    841 45        0.02  96.44
    842 46        0.02  96.46
    851 105        0.04 96.50
    861 5        0.00   96.50
    862 11        0.00  96.51
    869 11        0.00  96.51
    871 3,127        1.19   97.70
    872 58        0.02  97.72
    873 1,932        0.73   98.45
    874 2,743        1.04   99.50
    899 741        0.28 99.78
    912 156        0.06 99.84
    913 94        0.04  99.87
    919 102        0.04 99.91
    921 5        0.00   99.91
    922 40        0.02  99.93
    931 7        0.00   99.93
    944 17        0.01  99.94
    951 29        0.01  99.95
    962 20        0.01  99.96
    965 4        0.00   99.96
    966 16        0.01  99.96
    999 93        0.04  100.00
            
    Total   263,113      100.00
$\endgroup$

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