R Notebook

sleep2 <- reshape(sleep, direction = "wide",
                  idvar = "ID", timevar = "group")
sleep2[c("ID", "extra.1", "extra.2")]

t.test(Pair(extra.1, extra.2) ~ 1, data = sleep2)

    Paired t-test

data:  Pair(extra.1, extra.2)
t = -4.0621, df = 9, p-value = 0.002833
alternative hypothesis: true mean difference is not equal to 0
95 percent confidence interval:
 -2.4598858 -0.7001142
sample estimates:
mean difference 
          -1.58 

sleep$group1 <- as.numeric(sleep$group == 1)
sleep$group1

 [1] 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0

lm(extra ~ 0 + group1 + ID, data = sleep) |> summary()

Call:
lm(formula = extra ~ 0 + group1 + ID, data = sleep)

Residuals:
   Min     1Q Median     3Q    Max 
-1.510 -0.215  0.000  0.215  1.510 

Coefficients:
       Estimate Std. Error t value Pr(>|t|)    
group1   -1.580      0.389  -4.062 0.002833 ** 
ID1       2.090      0.645   3.240 0.010155 *  
ID2       0.390      0.645   0.605 0.560353    
ID3       1.240      0.645   1.922 0.086717 .  
ID4       0.240      0.645   0.372 0.718440    
ID5       0.690      0.645   1.070 0.312585    
ID6       4.690      0.645   7.271 4.71e-05 ***
ID7       5.390      0.645   8.356 1.56e-05 ***
ID8       1.990      0.645   3.085 0.013030 *  
ID9       3.090      0.645   4.791 0.000987 ***
ID10      3.490      0.645   5.411 0.000427 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

Residual standard error: 0.8697 on 9 degrees of freedom
Multiple R-squared:  0.9454,    Adjusted R-squared:  0.8788 
F-statistic: 14.18 on 11 and 9 DF,  p-value: 0.0002232