Announcement

Collapse
No announcement yet.
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Marginal Effects missing after applying Random Effect Probit Model

    Hello. I have a quick question? I estimated a static random effect probit model using xtprobit Y x1 x2 x3, re in > > > stata 14. > >after the computation, I have the coefficients of all included variables. After that I tried to estimate > > > Marginal effects using margins, dydx(*) predict(pu0). but unfortunately, I am not getting any value. you can see below: ------------------------------------------------------------------------------ | Delta-method | dy/dx Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- X1 | 0 (omitted) X2 | 0 (omitted) X3 | 0 (omitted) X4 | 0 (omitted) ------------------------------------------------------------------------------
    Can anyone guide me on what could be the possible problem and solution? why marginal effects are omitted?

  • #2
    Saad,

    Code:
    margins, dydx(*) predict(pu0)
    calculates the marginal effects on the probability of a positive outcome assuming the random effect is zero. I suspect that when you set the random effect to be zero, the predicted outcome is all positive or all negative, then you are not able to compute the marginal effects. You may try the code below to test my guess.

    Code:
    margins, predict(pu0)
    Moreover, you may reconsider whether the marginal effects above are what you need. Usually what we need is as below.

    Code:
    margins, dydx(*)

    Comment


    • #3
      Dear Fei Wang
      Thank you for your comment.
      by using this command:
      margins, dydx(*) , i get the same coefficients and output which I obtained through "xtprobit, re". through using "
      margins, predict(pu0)" I didnot get anything: see its output below: .
      . margins, predict(pu0)
      Warning: prediction constant over observations.

      Predictive margins Number of obs = 2,874
      Model VCE : OIM

      Expression : Pr(oexpdum=1 assuming u_i=0), predict(pu0)

      ------------------------------------------------------------------------------
      | Delta-method
      | Margin Std. Err. z P>|z| [95% Conf. Interval]
      -------------+----------------------------------------------------------------
      _cons | 1 . . . . .
      ------------------------------------------------------------------------------
      This issue can be resolved if I drop any variable (not specific) and re-run the codes. Thatswhy I confused why by adding all variables I donot get ME while if i drop any variable then it yields ME.

      Comment


      • #4
        Saad, indeed the prediction of probabilities is constant and that's why you were not able to compute the marginal effects. There might be some issues with your data but I'm not able to help more without further information.

        Comment

        Working...
        X