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  • Weighted panel regression in cross-country study

    Hello,

    I'm working on a cross country studies with various number of sample from each country for my thesis. My model is the following:
    Y = a + b*X + c*Z + d*I + e
    (panel data)

    where Y is individual level (company), X is country level variable, Z is control variables in country level, and I is control variables in individual level.

    In my sample, one of the countries accounts for 50% of the sample. I have 57 countries. I think this will be a problem because the country which has the most observation will have more weight and makes countries with small observation becoming less important. The result could be driven by the country that has the most observation.

    I have tried to find the solution and found one paper in a high impact journal (Journal of Finance) that has the same issue as mine. The authors use weighted regression by weighing the individual variables by the inverse number of the observation from each country. Then I found the weighted regression in the stata help (pweight, aweight, fweight) and some discussions related about it.

    However, I still do not know the technical aspect about these weighting options and I have not found the solution from the discussions I mentioned before.Therefore, I would like to ask which kind of weight option is appropriate for my case. I am a novice Stata user. I hope someone could kindly guide me on this.

    Thank you in advance

    Leo
    Last edited by Leo Indra Wardhana; 02 Sep 2015, 02:18.

  • #2
    Leo:
    welcome to the list.
    You may ant to try something like:
    Code:
    use "http://www.stata-press.com/data/r13/nlswork.dta", clear
    xtreg ln_wage age [aweight = 1/idcode], fe
    Kind regards,
    Carlo
    (Stata 19.0)

    Comment


    • #3
      Thank you Carlo

      I just found the technical note regarding aweight in the Stata guide. What I understand is that aweight option transforms the model estimation by multiplying it by the squared of the weight, which finally reduce the variance of the error, thus will solve heteroskedasticity problems (please kindly correct me if I'm wrong). Does this method could actually solve my problem I mentioned above,?

      Best regards,
      Leo

      Comment


      • #4
        Leo:
        I have to correct my previus reply, in that -aweight- are usually used in dealing with average values.
        A better solution for your problem might be:
        Code:
         use "http://www.stata-press.com/data/r13/nlswork.dta", clear
        xtreg ln_wage age [pweight = 1/idcode], fe vce(robust)
        Kind regards,
        Carlo
        (Stata 19.0)

        Comment


        • #5
          Hi Leo,

          I tried running a panel regression with aweight, however stata returns "weights not allowed", is there another option to panel regress and adjust for weights?

          Comment


          • #6
            you need to give us more information since some panel regression commands weights and others don't; start, as per the FAQ, with the exact command you gave to Stata

            Comment

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