load('sleep.Rdata')
notnassleep <- which(!is.na(sleep$TotalSleep))
L1 <- lm(log(sleep$BrainWt) ~ log(sleep$BodyWt), subset = notnassleep)
L2 <- lm(log(sleep$BrainWt) ~ sleep$TotalSleep, subset = notnassleep)
L3 <- lm(log(sleep$BrainWt) ~ log(sleep$BodyWt) + sleep$TotalSleep, subset = notnassleep)

summary(L1)

## 
## Call:
## lm(formula = log(sleep$BrainWt) ~ log(sleep$BodyWt), subset = notnassleep)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -1.7431 -0.4897 -0.0833  0.4388  1.8994 
## 
## Coefficients:
##                   Estimate Std. Error t value Pr(>|t|)    
## (Intercept)        2.15308    0.09906   21.73   <2e-16 ***
## log(sleep$BodyWt)  0.75911    0.03026   25.09   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.7071 on 56 degrees of freedom
## Multiple R-squared:  0.9183, Adjusted R-squared:  0.9168 
## F-statistic: 629.2 on 1 and 56 DF,  p-value: < 2.2e-16