A pre-loaded example dataset in R

Main page: https://www.rdocumentation.org/packages/datasets/versions/3.6.2/topics/chickwts

head(chickwts)
##   weight      feed
## 1    179 horsebean
## 2    160 horsebean
## 3    136 horsebean
## 4    227 horsebean
## 5    217 horsebean
## 6    168 horsebean
require(stats); require(graphics)
boxplot(weight ~ feed, data = chickwts, col = "lightgray",
    varwidth = TRUE, notch = TRUE, main = "chickwt data",
    ylab = "Weight at six weeks (gm)")
## Warning in bxp(list(stats = structure(c(216, 271.5, 342, 373.5, 404, 108, : some
## notches went outside hinges ('box'): maybe set notch=FALSE

anova(fm1 <- lm(weight ~ feed, data = chickwts))
## Analysis of Variance Table
## 
## Response: weight
##           Df Sum Sq Mean Sq F value    Pr(>F)    
## feed       5 231129   46226  15.365 5.936e-10 ***
## Residuals 65 195556    3009                      
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
opar <- par(mfrow = c(2, 2), oma = c(0, 0, 1.1, 0),
            mar = c(4.1, 4.1, 2.1, 1.1))
plot(fm1)

par(opar)