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  • Absorbing fixed effects in probit (pooled cross section data)

    Hi all
    I am trying to estimate the impact of firm-level GVC (a binary variable) on firm env innovation (a binary variable) using WBES dataset of 41 countries and 3 years. The dataset is pooled cross-section and not panel. I am trying to run a probit model while accounting for country, year and industry fixed effects, but chi-square is reported as missing. If I understand correctly from other threads, that may be due to having lots of parameters in the model that absorbed much of the heterogeneity in the Y variable. My question is how to account for all these fixed effects in a probit model, Is there any code I can use to absorb them in probit or is there another model I can run to fit my data and the control of fixed effects? I have also read once that I can ignore the missing chi square but not that sure what can be the consequences of doing this? I have tried to run LPM with absorb fixed but at later stages of my analysis, I need to do instrumentation, which is by eprobit so I will have to go back to the probit model.

    Thanks in advance !!

    Here are the codes that I have used so far
    probit innov GVC Xs i.year i.country i.industry_type [pw=wweak ], robust cluster (country)
    reghdfe innov GVC Xs [pw=wweak ], absorb (year country industry_type) cluster (country)

    Here are the results of probit
    probit innov GVC_weak large_firm small_firm ln_age employee_training FC knowledge_dev NIQ ln_subsidy MANG_score_alt2 reg customer_certificate strategic_involovement i.year i.a1 i.industry_type [pw=wweak ], r
    > obust cluster (a1)

    Iteration 0: log pseudolikelihood = -2483275.1
    Iteration 1: log pseudolikelihood = -1959170.7
    Iteration 2: log pseudolikelihood = -1949453.4
    Iteration 3: log pseudolikelihood = -1949444.4
    Iteration 4: log pseudolikelihood = -1949444.4

    Probit regression Number of obs = 19,509
    Wald chi2(16) = .
    Prob > chi2 = .
    Log pseudolikelihood = -1949444.4 Pseudo R2 = 0.2150

    (Std. err. adjusted for 35 clusters in a1)
    --------------------------------------------------------------------------------------------
    | Robust
    innov | Coefficient std. err. z P>|z| [95% conf. interval]
    ---------------------------+----------------------------------------------------------------
    GVC_weak | .3604266 .1203145 3.00 0.003 .1246145 .5962386
    large_firm | .0645271 .0998798 0.65 0.518 -.1312336 .2602879
    small_firm | .0471583 .1121527 0.42 0.674 -.172657 .2669735
    ln_age | .168977 .0622416 2.71 0.007 .0469856 .2909683
    employee_training | .0158048 .1107269 0.14 0.886 -.201216 .2328257
    FC | -.0728579 .1086594 -0.67 0.503 -.2858264 .1401106
    knowledge_dev | .4785452 .2641452 1.81 0.070 -.0391698 .9962602
    NIQ | .4808054 .2457795 1.96 0.050 -.0009136 .9625245
    ln_subsidy | .4180203 .2953128 1.42 0.157 -.1607822 .9968228
    MANG_score_alt2 | 2.398323 .2487607 9.64 0.000 1.910761 2.885885
    reg | .1319785 .1980638 0.67 0.505 -.2562194 .5201764
    customer_certificate | .3304099 .0949439 3.48 0.001 .1443233 .5164965
    strategic_involovement | .1718978 .1160677 1.48 0.139 -.0555907 .3993863
    |
    year |
    2019 | .0518758 .0914128 0.57 0.570 -.1272901 .2310417
    2020 | .5371449 .2227458 2.41 0.016 .1005711 .9737187
    |
    a1 |
    Morocco | -.5929384 .5425835 -1.09 0.274 -1.656382 .4705057
    Albania | 1.358481 .4062889 3.34 0.001 .5621698 2.154793
    Georgia | 1.944364 1.07398 1.81 0.070 -.1605977 4.049326
    Tajikistan | -.6343332 .1884926 -3.37 0.001 -1.003772 -.2648946
    Turkey | -1.268857 .7705144 -1.65 0.100 -2.779037 .2413234
    Ukraine | -.649828 .6056447 -1.07 0.283 -1.83687 .5372139
    Uzbekistan | -.5938551 .8388376 -0.71 0.479 -2.237946 1.050236
    Russia | -1.939941 1.388275 -1.40 0.162 -4.660911 .7810287
    Poland | -.6432855 .6180704 -1.04 0.298 -1.854681 .5681102
    Romania | -.8916952 .4496054 -1.98 0.047 -1.772906 -.0104848
    Serbia | -.063677 .1290953 -0.49 0.622 -.3166992 .1893452
    Kazakhstan | -.9848711 .8556733 -1.15 0.250 -2.66196 .6922178
    Moldova | .9573349 .4271374 2.24 0.025 .120161 1.794509
    Bosnia and Herzegovina | 1.191216 .4027597 2.96 0.003 .4018213 1.98061
    Azerbaijan | -.6784546 .504745 -1.34 0.179 -1.667737 .3108273
    North Macedonia | -.0224012 .0504192 -0.44 0.657 -.1212211 .0764186
    Armenia | 1.962945 .8488859 2.31 0.021 .299159 3.62673
    Kyrgyz Republic | -.4837911 .2442355 -1.98 0.048 -.9624839 -.0050983
    Mongolia | .8027477 .0549015 14.62 0.000 .6951428 .9103525
    Estonia | 1.546961 .5356801 2.89 0.004 .4970475 2.596875
    Czechia | .7792579 .0996308 7.82 0.000 .5839851 .9745306
    Hungary | .7761078 .136825 5.67 0.000 .5079357 1.04428
    Latvia | .7420941 .0935974 7.93 0.000 .5586466 .9255417
    Lithuania | .3934754 .0966013 4.07 0.000 .2041402 .5828105
    Slovak Republic | .7567628 .1112149 6.80 0.000 .5387856 .9747401
    Slovenia | .8335099 .2871212 2.90 0.004 .2707627 1.396257
    Bulgaria | -.3715321 .4377153 -0.85 0.396 -1.229438 .486374
    Egypt | -1.876557 1.169642 -1.60 0.109 -4.169014 .4158996
    Greece | -.008544 .5898928 -0.01 0.988 -1.164713 1.147625
    Portugal | .4442348 .2110546 2.10 0.035 .0305753 .8578943
    Lebanon | -.7562414 .6536081 -1.16 0.247 -2.03729 .5248069
    Tunisia | -.207709 .2819669 -0.74 0.461 -.7603539 .3449359
    Cyprus | 1.326577 .1531103 8.66 0.000 1.026486 1.626667
    Italy | -1.164064 1.091522 -1.07 0.286 -3.303408 .9752809
    |
    industry_type |
    Retail services | -.0696127 .0383865 -1.81 0.070 -.1448487 .0056234
    Other services | -.0344265 .0412406 -0.83 0.404 -.1152566 .0464036
    |
    _cons | -3.703088 1.788344 -2.07 0.038 -7.208178 -.197997
    --------------------------------------------------------------------------------------------

    Here are the results of LPM with absorbed fixed effects
    reghdfe innov GVC_weak large_firm small_firm ln_age employee_training FC knowledge_dev NIQ ln_subsidy MANG_score_alt2 reg customer_certificate strategic_involovement [pw=wweak ], absorb (a1 year industry_type
    > ) cluster (a1)
    (MWFE estimator converged in 6 iterations)

    HDFE Linear regression Number of obs = 19,509
    Absorbing 3 HDFE groups F( 13, 34) = 773.03
    Statistics robust to heteroskedasticity Prob > F = 0.0000
    R-squared = 0.2447
    Adj R-squared = 0.2427
    Within R-sq. = 0.2129
    Number of clusters (a1) = 35 Root MSE = 0.4340

    (Std. err. adjusted for 35 clusters in a1)
    --------------------------------------------------------------------------------------------
    | Robust
    innov| Coefficient std. err. t P>|t| [95% conf. interval]
    ---------------------------+----------------------------------------------------------------
    GVC_weak | .0854028 .0398036 2.15 0.039 .0045122 .1662935
    large_firm | -.0088717 .0296829 -0.30 0.767 -.0691946 .0514512
    small_firm | .0181906 .0349781 0.52 0.606 -.0528935 .0892746
    ln_age | .0500536 .0198766 2.52 0.017 .0096594 .0904477
    employee_training | .0025855 .0325173 0.08 0.937 -.0634976 .0686687
    FC | -.023247 .0338457 -0.69 0.497 -.0920298 .0455358
    knowledge_dev | .1120606 .0668292 1.68 0.103 -.0237526 .2478738
    NIQ | .1591949 .0770409 2.07 0.046 .0026289 .315761
    ln_subsidy | .0761537 .0738407 1.03 0.310 -.0739087 .226216
    MANG_score_alt2 | .7037628 .0573147 12.28 0.000 .5872855 .8202402
    reg | .0337931 .0594995 0.57 0.574 -.0871244 .1547105
    customer_certificate | .0859756 .0292428 2.94 0.006 .0265471 .145404
    strategic_involovement | .0223843 .0253451 0.88 0.383 -.0291231 .0738916
    _cons | -.4777069 .6464486 -0.74 0.465 -1.791449 .8360347
    --------------------------------------------------------------------------------------------

    Absorbed degrees of freedom:
    -------------------------------------------------------+
    Absorbed FE | Categories - Redundant = Num. Coefs |
    ---------------+---------------------------------------|
    a1 | 35 35 0 *|
    year | 3 1 2 |
    industry_type | 3 1 2 |
    -------------------------------------------------------+
    * = FE nested within cluster; treated as redundant for DoF computation

    .

  • #2
    I don't see why you need to absorb the country, industry, and year dummies instead of entering them explicitly in the regression. You have only 35 countries, 3 years, and 3 industries. As far as I can tell, your probit regression looks fine. The Wald \(\chi^2\) statistic cannot be computed due to clustering, which limits the degrees of freedom available (your effective number of observations is 35 if clustering). It functions similarly to the F-statistic for joint significance of all regressors in a linear regression model and does not provide additional insights beyond what can be inferred from the individual coefficients. Therefore, just proceed with the probit regression and disregard the missing statistic.
    Last edited by Andrew Musau; Yesterday, 06:59.

    Comment


    • #3
      Greatly appreciated, Thank you!!!

      Comment

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