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  • Historical Data Small-N: reg or xtgls?

    Dear Statalist Community,

    I really could use your help, as I am confused on what model to choose, considering the data I have. My dependent variable (voteshare) consists on the vote-share in a party in a given election at the municipality level (8,108 observations).

    However, because my independent variables -- decline and growth -- consist of historical data portraying the lower economic growth (decline) and higher economic growth (growth) during a particular historical period precceding the election, this data is only available at the provincial level, and there are only 50 provinces.

    Should I:

    1. Ignore this, and run a normal:
    reg voteshare decline growth [controls], r

    2. Should I treat my DV as a "small N, large T", being N the number of provinces (N=50) and the T the number of municipalities within each province, with:
    xtset province
    and run a xtgls or xtregar ?

    3. I tried using a DV N=50 with the voteshare of each province instead of municipalities, but the results look really strange... Although the scatterplots clearly show that the provinces that experienced a higher decline period have a lower voteshare, and the provinces that exprienced more growth have a higher voteshare (which is in accordance with my theoretical expectations) (Y axis=voteshare):

    Click image for larger version

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    Click image for larger version

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    However, my regression does not portray these relationships, even without controls:

    . reg voteshare growth decline, r

    Linear regression Number of obs = 50
    F(2, 47) = 7.21
    Prob > F = 0.0019
    R-squared = 0.2791
    Root MSE = .13951

    ------------------------------------------------------------------------------
    | Robust
    voteshare | Coef. Std. Err. t P>|t| [95% Conf. Interval]
    -------------+----------------------------------------------------------------
    growth | 1.004445 .689592 1.46 0.152 -.3828348 2.391726
    decline | -1.007512 .820127 -1.23 0.225 -2.657395 .6423708
    _cons | .4703362 .0223719 21.02 0.000 .4253298 .5153427
    ------------------------------------------------------------------------------

    I don't know why this might be and I am not sure this N=50 province-level analysis is the best solution.


    4. Bayesian model? However I don't know how to go about the priors.

    I really could use your advice!

    Thank you very much!
    Last edited by Cat Santos; 23 Feb 2022, 03:39.
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