+ Reply to Thread
Results 1 to 2 of 2

Thread: Ordinal predictor variable in regression

  1. #1
    Fortran must die
    Points: 58,790, Level: 100
    Level completed: 0%, Points required for next Level: 0
    noetsi's Avatar
    Posts
    6,532
    Thanks
    692
    Thanked 915 Times in 874 Posts

    Ordinal predictor variable in regression




    When you have a nominal categorical predictor you just create dummies. With say a five level ordinal predictor (the classical case would be a likert scale predictor) do you just use the raw variable as the predictor? I always thought so, because the distribution or number of unique levels of the IV did not enter into the regression assumptions.

    But recently a proff of mine said that doing this, say using a 5 point likert predictor, could generate nonsensical results.

    Any suggestions?
    "Very few theories have been abandoned because they were found to be invalid on the basis of empirical evidence...." Spanos, 1995

  2. #2
    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

    Re: Ordinal predictor variable in regression


    Hello!

    From my understanding, ordinal predictors are different from those "truly" categorical in that the "distance" between, say, 1 and 2, 2 and 3, 3 and 4, etc. is the same. Under this assumption, using a likert predictor as a continuous scale is plausible. On top of that, I came across a paper, which argues that with more than 8 (as far as I remember) categories, there is no difference at all. I can provide you with more references on this assumption, if interested.
    Lastly, it is possible to compute the predicted values for the dichotomized and "scale" predictors and examine the correlations between them.

+ Reply to 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