Basic model with two lags of dependent variable included as regressors
        . xtabond n l(0/1).w l(0/2).(k ys) yr1980-yr1984, lags(2)
        . xtabond n l(0/1).w l(0/2).(k ys) yr1980-yr1984, lags(2) vce(robust)
        . xtabond n l(0/1).w l(0/2).(k ys) yr1980-yr1984, lags(2) twostep

    Treat w and k as predetermined and include w, L.w, k, L.k, and L2.k as additional
    regressors
        . xtabond n l(0/2).ys yr1980-yr1984, lags(2) pre(w, lag(1,.)) pre(k, lag(2,.))

    Treat L.w and L2.k as endogenous and include w, L.w, k, L.k, and L2.k as additional
    regressors
        . xtabond n l(0/2).ys yr1980-yr1984, lags(2) endogenous(w, lag(1,.)) endogenous(k,
            lag(2,.))

w4的滞后一期和s4 e4 t4 f4 q4的滞后2期

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