> rm(list=ls())
> a=read.table("D:/练习.txt",header=T)
> round(a[1:10,],2)
    X    y
1  -1 -0.9
2  -2 -2.0
3  -3 -3.1
4  -4 -3.9
5  -5 -5.1
6   5  5.0
7   4  4.1
8   3  2.9
9   2  2.1
10  1  0.9
> round(cor(a),3)
  X y
X 1 1
y 1 1
> lm1=lm(y~X,data=a)
> summary(lm1)

Call:
lm(formula = y ~ X, data = a)

Residuals:
      Min        1Q    Median        3Q       Max
-0.113636 -0.084091 -0.006818  0.088636  0.118182

Coefficients:
              Estimate Std. Error   t value Pr(>|t|)   
(Intercept) -1.488e-17  3.117e-02 -4.77e-16        1   
X            1.005e+00  9.398e-03     106.9 6.56e-14 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.09857 on 8 degrees of freedom
Multiple R-squared: 0.9993,     Adjusted R-squared: 0.9992
F-statistic: 1.142e+04 on 1 and 8 DF,  p-value: 6.557e-14

另外完全正相关的数据为什么还存在残差项标准差呢？