[R] AIC and BIC in mixed effects model

Dear R Users: I am trying to compare several structures of the within-patient covariance such as unstructured, Autoregressive, and spatial by using the MIXED effects model. Can AIC, BIC be negative ? If yes, then in what situations they may be negative. Thanks a lot. [[alternative HTML

Re: [R] AIC and BIC in mixed effects model

Chuanjun Zhang zhangchu at umkc.edu writes: Dear R Users: I am trying to compare several structures of the within-patient covariance such as unstructured, Autoregressive, and spatial by using the MIXED effects model. Can AIC, BIC be negative ? If yes, then in what situations they may be