datos1<-read.table("ma2.csv", sep = ",", header=T)
datos1
##    densidad   masa
## 1      1566 0.1481
## 2      1566 0.1954
## 3      1562 0.2204
## 4      1562 0.1207
## 5      1542 0.2920
## 6      1542 0.3892
## 7      1540 0.3837
## 8      1540 0.2994
## 9      1538 0.2892
## 10     1538 0.1347
## 11     1536 0.2254
## 12     1536 0.7405
## 13     1518 0.4069
## 14     1518 0.1213
## 15     1516 0.2477
## 16     1516 0.3641
## 17     1514 0.4780
## 18     1514 0.3243
## 19     1512 0.7489
## 20     1512 0.8562
## 21     1494 0.5270
## 22     1494 0.4817
## 23     1492 0.3918
## 24     1492 0.3449
## 25     1490 0.3349
## 26     1490 0.6067
## 27     1488 0.5888
## 28     1488 1.0516
## 29     1470 0.4802
## 30     1470 1.7754
## 31     1468 1.4030
## 32     1468 0.9107
## 33     1466 0.5893
## 34     1466 1.2156
## 35     1464 1.3592
## 36     1464 1.8306
## 37     1446 1.6102
## 38     1446 1.6628
## 39     1446 1.3939
## 40     1446 1.8325
## 41     1444 1.7633
## 42     1444 1.2809
## 43     1444 1.7984
## 44     1444 2.0020
## 45     1442 1.4276
## 46     1442 1.9924
## 47     1442 1.8784
## 48     1442 1.2773
## 49     1440 1.2808
## 50     1440 1.7115
## 51     1440 1.9192
## 52     1440 1.6359
## 53     1422 2.8007
## 54     1422 2.7597
## 55     1422 2.2568
## 56     1419 1.9971
## 57     1419 1.4329
## 58     1419 2.8216
## 59     1419 2.4322
## 60     1416 2.8792
## 61     1416 1.7876
## 62     1416 1.8798
## 63     1416 2.0045
attach(datos1)
plot (masa, densidad, ylim=c(1350, 1600))
fit1<-lm(densidad~masa)
fit1
## 
## Call:
## lm(formula = densidad ~ masa)
## 
## Coefficients:
## (Intercept)         masa  
##     1534.77       -50.34
abline(fit1)
segments(masa, fitted(fit1), masa, densidad)

summary(fit1)
## 
## Call:
## lm(formula = densidad ~ masa)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -43.638 -16.823  -0.239  19.048  41.070 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept) 1534.766      4.814  318.82   <2e-16 ***
## masa         -50.337      3.439  -14.64   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 21.82 on 61 degrees of freedom
## Multiple R-squared:  0.7784, Adjusted R-squared:  0.7748 
## F-statistic: 214.3 on 1 and 61 DF,  p-value: < 2.2e-16
anova(fit1)
## Analysis of Variance Table
## 
## Response: densidad
##           Df Sum Sq Mean Sq F value    Pr(>F)    
## masa       1 102063  102063   214.3 < 2.2e-16 ***
## Residuals 61  29051     476                      
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
layout(matrix(1:4,2,2))
plot(fit1)

layout(1)
shapiro.test(fit1$residuals)
## 
##  Shapiro-Wilk normality test
## 
## data:  fit1$residuals
## W = 0.97721, p-value = 0.2922
datos1.tra<-transform(datos1,densidad=log10(densidad), masa=log10(masa))
detach(datos1)
attach(datos1.tra)
plot (masa, densidad)
fit1<-lm(densidad~masa)
fit1
## 
## Call:
## lm(formula = densidad ~ masa)
## 
## Coefficients:
## (Intercept)         masa  
##     3.16651     -0.03094
abline(fit1)
segments(masa, fitted(fit1), masa, densidad)

summary(fit1)
## 
## Call:
## lm(formula = densidad ~ masa)
## 
## Residuals:
##        Min         1Q     Median         3Q        Max 
## -0.0135848 -0.0031897 -0.0000396  0.0029161  0.0158433 
## 
## Coefficients:
##               Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  3.1665110  0.0007173 4414.35   <2e-16 ***
## masa        -0.0309402  0.0017819  -17.36   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.005564 on 61 degrees of freedom
## Multiple R-squared:  0.8317, Adjusted R-squared:  0.829 
## F-statistic: 301.5 on 1 and 61 DF,  p-value: < 2.2e-16
anova(fit1)
## Analysis of Variance Table
## 
## Response: densidad
##           Df    Sum Sq   Mean Sq F value    Pr(>F)    
## masa       1 0.0093346 0.0093346   301.5 < 2.2e-16 ***
## Residuals 61 0.0018886 0.0000310                      
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
layout(matrix(1:4,2,2))
plot(fit1)

layout(1)
shapiro.test(fit1$residuals)
## 
##  Shapiro-Wilk normality test
## 
## data:  fit1$residuals
## W = 0.98995, p-value = 0.889