• A glance at the data of chicken weight

data(ChickWeight)

• Average weight of chicks on different diets

group_by(ChickWeight, Diet) %>%
  summarise(mean(weight))

## # A tibble: 4 × 2
##     Diet `mean(weight)`
##   <fctr>          <dbl>
## 1      1       102.6455
## 2      2       122.6167
## 3      3       142.9500
## 4      4       135.2627

(Choose the individual diet group from the dropdown menu)

Conclusion: Chicks on diet 3 grow more than others.