请问各位大神R语言多元线性回归后模型中的 Estimate值为什么不是常数？这样就没有办法分析经济意义了。
代码是：
toothpaste<-data.frame(
X1=c(1.74012,-0.46546,-2.01224,2.97181,0.96673,0.90945,-0.20767,0.45114,0.79487,0.73758,0.27928,-0.26496,-0.06445,-0.78055,-0.40818,-0.80919,-0.78055,-0.37953,-0.37953,-0.37953,-0.15038,-0.58004,-0.60868,-0.58004),
X2=c(2.76538,1.57086,1.08886,-0.21044,-0.0847,-0.14757,-0.44096,-0.902,-0.39905,-1.0487,-0.35713,0.98408,1.40321,0.81643,0.29252,0.3973,-0.92296,-0.81818,-0.0847,-0.35713,-0.44096,-0.60861,-1.09061,-1.40496),
X3=c(3.63039,2.19697,-0.3607,-0.92282,-0.3607,0.00468,-0.41691,-0.41691,-0.27638,-0.07963,-0.02342,-0.44502,0.22953,-0.19206,0.39817,0.59492,0.34196,-0.16395,-0.30448,-0.50123,-0.64176,-0.78229,-0.72608,-0.78229),
Y=c(3.38107,1.83677,0.54518,-0.35332,-0.18485,-0.10061,-0.52178,-0.85872,-0.38139,-0.71833,-0.241,0.37671,1.02251,0.40479,0.40479,0.57326,-0.43755,-0.60602,-0.15677,-0.46563,-0.54986,-0.74641,-0.99911,-1.22374)
)
  lm.sol<-lm(Y~X1+X2+X3,data = toothpaste)
  summary(lm.sol)