程序如下:
library(mvtnorm)
nm<-100
p<-10
rmat<-diag(p)
x<-rmvnorm(nm,mean=rep(0,p),sigma=rmat)
eps<-rnorm(nm,mean=0,1)
y<-x[,1]+x[,2]+x[,3]+x[,4]+x[,5]+eps
a<-lm(y~0+x)
结果如下:
Call:
lm(formula = y ~ 0 + x)
Coefficients:
x1 x2 x3 x4 x5 x6 x7
1.164506 0.938315 0.766277 1.091936 0.994549 0.184499 -0.102038
x8 x9 x10
0.194357 0.017017 -0.006841
问题如下:
真实值只与x1-x5有关,为何差别那么大?