初学stata，按照书上的用GMM检验后得到结论，但是不懂什么意思，这是说原假设都不能拒绝么？恳请哪位大神帮忙解释一下，谢谢了
. estat abond

Arellano-Bond test for zero autocorrelation in first-differenced errors
  +-----------------------+
  |Order |  z     Prob > z|
  |------+----------------|
  |   1  |-2.7513  0.0059 |
  |   2  | .90839  0.3637 |
  +-----------------------+
   H0: no autocorrelation


. estat sargan
Sargan test of overidentifying restrictions
        H0: overidentifying restrictions are valid

        chi2(60)     =  53.94741
        Prob > chi2  =    0.6953