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如何在ivreg模型中包含虚拟变量?

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我有以下型号:

ivreg ldemand social_housing transport year (lprice = utilities)

但是,我想将 year 作为虚拟变量 .

我怎么能在Stata中做到这一点?

使用 i.year 不适用于 ivreg 命令 .

交叉发布于Statalist .

1 回答

  • 1

    命令 ivreg 不允许因子变量:

    . webuse hsng2, clear
    
    . ivreg rent pcturban i.region (hsngval = faminc)
    factor variables not allowed
    r(101);
    

    但是,您仍然可以使用 xi 前缀来动态创建虚拟对象:

    .  xi: ivreg rent pcturban  i.region (hsngval = faminc)
    i.region          _Iregion_1-4        (naturally coded; _Iregion_1 omitted)
    
    Instrumental variables (2SLS) regression
    
          Source |       SS           df       MS      Number of obs   =        50
    -------------+----------------------------------   F(5, 44)        =      9.10
           Model |  12735.4667         5  2547.09334   Prob > F        =    0.0000
        Residual |  48507.6533        44  1102.44667   R-squared       =    0.2079
    -------------+----------------------------------   Adj R-squared   =    0.1179
           Total |    61243.12        49  1249.85959   Root MSE        =    33.203
    
    ------------------------------------------------------------------------------
            rent |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
    -------------+----------------------------------------------------------------
         hsngval |   .0038683   .0008958     4.32   0.000     .0020629    .0056737
        pcturban |  -.4980121   .5179779    -0.96   0.342    -1.541928    .5459039
      _Iregion_2 |   1.528672   15.14086     0.10   0.920    -28.98572    32.04306
      _Iregion_3 |    7.74279   15.10906     0.51   0.611    -22.70752     38.1931
      _Iregion_4 |  -40.61235   19.60999    -2.07   0.044    -80.13369   -1.091002
           _cons |   88.26681   31.69154     2.79   0.008     24.39671    152.1369
    ------------------------------------------------------------------------------
    Instrumented:  hsngval
    Instruments:   pcturban _Iregion_2 _Iregion_3 _Iregion_4 faminc
    ------------------------------------------------------------------------------
    

    请务必注意,根据命令的帮助文件:

    从Stata 10开始,过时的命令ivreg是一个过时的命令.ivreg已被ivregress命令取代 .

    因此,最好切换到 ivregress

    . ivregress 2sls rent pcturban i.region (hsngval = faminc), small
    
    Instrumental variables (2SLS) regression
    
          Source |       SS       df       MS         Number of obs   =         50
    -------------+------------------------------      F(  5,    44)   =       9.10
           Model |  12735.4667     5  2547.09334      Prob > F        =     0.0000
        Residual |  48507.6533    44  1102.44667      R-squared       =     0.2079
    -------------+------------------------------      Adj R-squared   =     0.1179
           Total |    61243.12    49  1249.85959      Root MSE        =     33.203
    
    ------------------------------------------------------------------------------
            rent |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
    -------------+----------------------------------------------------------------
         hsngval |   .0038683   .0008958     4.32   0.000     .0020629    .0056737
        pcturban |  -.4980121   .5179779    -0.96   0.342    -1.541928    .5459039
                 |
          region |
        N Cntrl  |   1.528672   15.14086     0.10   0.920    -28.98572    32.04306
          South  |    7.74279   15.10906     0.51   0.611    -22.70752     38.1931
           West  |  -40.61235   19.60999    -2.07   0.044    -80.13369   -1.091002
                 |
           _cons |   88.26681   31.69154     2.79   0.008     24.39671    152.1369
    ------------------------------------------------------------------------------
    Instrumented:  hsngval
    Instruments:   pcturban 2.region 3.region 4.region faminc
    

    在Stata的命令提示符下键入 help ivregress 以获取更多详细信息 .

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