stata16这个是自带的命令，不需要下载

请问stata15没有是嘛

安装了stata16，还是没有xttest0这个命令啊，也没有找到

Stata15里面就有
下面是帮助文件里面看到的信息阿

[XT] xtreg postestimation -- Postestimation tools for xtreg
                             (View complete PDF manual entry)


Postestimation commands

    The following postestimation commands are of special interest after xtreg:

    Command              Description
    ---------------------------------------------------------------------------------------
    xttest0              Breusch and Pagan LM test for random effects
    ---------------------------------------------------------------------------------------

    The following standard postestimation commands are also available:

    Command            Description
    ---------------------------------------------------------------------------------------
      contrast         contrasts and ANOVA-style joint tests of estimates
    * estat ic         Akaike's and Schwarz's Bayesian information criteria (AIC and BIC)
      estat summarize  summary statistics for the estimation sample
      estat vce        variance-covariance matrix of the estimators (VCE)
      estimates        cataloging estimation results
    + forecast         dynamic forecasts and simulations
      hausman          Hausman's specification test
      lincom           point estimates, standard errors, testing, and inference for linear
                         combinations of coefficients
    * lrtest           likelihood-ratio test
      margins          marginal means, predictive margins, marginal effects, and average
                         marginal effects
      marginsplot      graph the results from margins (profile plots, interaction plots,
                         etc.)
      nlcom            point estimates, standard errors, testing, and inference for
                         nonlinear combinations of coefficients
      predict          predictions, residuals, influence statistics, and other diagnostic
                         measures
      predictnl        point estimates, standard errors, testing, and inference for
                         generalized predictions
      pwcompare        pairwise comparisons of estimates
      test             Wald tests of simple and composite linear hypotheses
      testnl           Wald tests of nonlinear hypotheses
    ---------------------------------------------------------------------------------------
    * estat ic and lrtest are not appropriate after xtreg with the pa or re option.
    + forecast is not appropriate with mi estimation results.

可以输入help xttest进行下载哈