+ Reply to Thread
Results 1 to 1 of 1

Thread: What can the standard errors tell me?

  1. #1
    Points: 4,664, Level: 43
    Level completed: 57%, Points required for next Level: 86
    kiton's Avatar
    Location
    Corn field
    Posts
    234
    Thanks
    47
    Thanked 51 Times in 46 Posts

    What can the standard errors tell me?




    Hello dear forum members!

    I wanted to share with you a couple graphs and seek your wisdom on the insights that I may be omitting.

    According to theory, there are merits to believe that relationship b/w X and Y is moderated by M. Notably, the relationship between X and M is likely to be quadratic. Following Aiken and West (1991), to test for the quadratic interaction I estimate the following model:

    y = X + M + X*M + M^2 + X*M^2, in which case X*M^2 would give a test of quadratic relationship. Also, y is of a count type, therefore I use a Poisson estimator.

    Now, when I plot the interaction (i.e., impact of X on Y at representative values of M [obtained using Stata's -margins- command]) in terms of average marginal effect I get the two graphs as attached. One is with default standard errors and another one with robust SEs (estimated using so-called "delta method"), as mentioned in the literature to account for the fact that we cannot fully assume Poisson distribution.

    The pattern of the confidence intervals on the "robust SE" graph seems somewhat interesting. What can it possibly be an indicator of? E.g., I could have suspected there is another "interacting variable" that might boost or suppress the impact. Or it could be that the magnitude of impact is better predicted closer to value of zero, while beyond some threshold it becomes less efficient.

    Any ideas are welcome.
    Attached Thumbnails Attached Thumbnails Click image for larger version

Name:	Screen Shot 2016-11-05 at 20.39.25.jpg‎
Views:	19
Size:	12.8 KB
ID:	6306   Click image for larger version

Name:	Screen Shot 2016-11-03 at 14.17.54.jpg‎
Views:	14
Size:	16.5 KB
ID:	6307  

+ Reply to Thread

           




Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts






Advertise on Talk Stats