studynum <-c(1, 2, 3, 4, 5)

y <-c(0.284, 0.224, 0.360, 0.785, 0.492)

w <-c(14.63, 17.02, 9.08, 33.03, 5.63)

genData2 <-data.frame(cbind(studynum, y, w))

library(nlme)

re.teo<-lme(y~1,data=genData2,random=~1|studynum, method="REML", weights=varFixed(~w))

summary(re.teo)

运行结果如下：

Linear mixed-effects model fit by REML

Data: genData2

       AIC      BIC     logLik

   5.033622    3.192505  0.483189

Random effects:

Formula: ~1 | studynum

         (Intercept)     Residual

StdDev: 4.205259e-06   0.04701933

Variance function:

Structure: fixed weights

Formula: ~w

Fixed effects: y ~ 1

                Value  Std.Error   DF     t-value     p-value

(Intercept)   0.4119562   0.0704743   5    5.845481     0.0021

此处的自由度为什么是5？

Standardized Within-Group Residuals:

         1          2          3          4          5

-0.7114801 -0.9689479 -0.3667061  1.3804766  0.7174588

attr(,"label")

[1] "Standardized residuals"

Number of Observations: 5

Number of Groups: 5