R语言plm包的pgmm()函数,显示的错误为:
Error in solve.default(crossprod(WX, t(crossprod(WX,A1)))) :
Lapack routinedgesv: system is exactly singular: U[5,5] = 0
In addition: Warning message:
In pgmm(Static_form, data = GLMMs_Dat_Frame, index =c("Subject_ID", :
the first-stepmatrix is singular, a general inverse is used
哪位大神能够指点指点怎么破呢?