> toluca <- read.table("C:\\data\\CH01TA01.txt",header=F,col.names=c("X","Y"))
> 
> attach(toluca)
The following object(s) are masked from 'toluca (position 3)':

    X, Y
> 
> toluca
     X   Y
1   80 399
2   30 121
3   50 221
4   90 376
5   70 361
6   60 224
7  120 546
8   80 352
9  100 353
10  50 157
11  40 160
12  70 252
13  90 389
14  20 113
15 110 435
16 100 420
17  30 212
18  50 268
19  90 377
20 110 421
21  30 273
22  90 468
23  40 244
24  80 342
25  70 323
> 
> plot(X,Y)
> 
> n <- length(Y)
> 
> mean_x <- mean(X); mean_y <- mean(Y)
> var_x <- var(X);  var_y <- var(Y);  cov_xy <- cov(X,Y)
> 
> SS_xx <- (n-1)*var_x
> SS_xy <- (n-1)*cov_xy
> SS_yy <- (n-1)*var_y
> 
> b1 <- SS_xy/SS_xx
> b0 <- mean_y - b1*mean_x
> 
> yhat <- b0 + b1*X
> e <- Y-yhat
> 
> SSE <- sum(e^2)
> MSE <- SSE/(n-2)
> s <- sqrt(MSE)
> 
> print(cbind(mean_x,mean_y))
     mean_x mean_y
[1,]     70 312.28
> print(cbind(SS_xx,SS_xy,SS_yy))
     SS_xx SS_xy  SS_yy
[1,] 19800 70690 307203
> print(cbind(b0,b1))
           b0       b1
[1,] 62.36586 3.570202
> print(cbind(Y,yhat,e))
        Y     yhat           e
 [1,] 399 347.9820  51.0179798
 [2,] 121 169.4719 -48.4719192
 [3,] 221 240.8760 -19.8759596
 [4,] 376 383.6840  -7.6840404
 [5,] 361 312.2800  48.7200000
 [6,] 224 276.5780 -52.5779798
 [7,] 546 490.7901  55.2098990
 [8,] 352 347.9820   4.0179798
 [9,] 353 419.3861 -66.3860606
[10,] 157 240.8760 -83.8759596
[11,] 160 205.1739 -45.1739394
[12,] 252 312.2800 -60.2800000
[13,] 389 383.6840   5.3159596
[14,] 113 133.7699 -20.7698990
[15,] 435 455.0881 -20.0880808
[16,] 420 419.3861   0.6139394
[17,] 212 169.4719  42.5280808
[18,] 268 240.8760  27.1240404
[19,] 377 383.6840  -6.6840404
[20,] 421 455.0881 -34.0880808
[21,] 273 169.4719 103.5280808
[22,] 468 383.6840  84.3159596
[23,] 244 205.1739  38.8260606
[24,] 342 347.9820  -5.9820202
[25,] 323 312.2800  10.7200000
> 
> plot(X,Y,xlim=c(0,125))
> abline(a=b0,b=b1)  
>