Awesome! Now, let's see why
summarise() are so great together.
If we wanted to calculate the mean and median populations in groups defined by continent, we'd write:
mean_pop = mean(population),
median_pop = median(population))
What do you think this will return? Well, we know that
summarise() will return the median and mean populations. And
group_by() will organize the information by continent. Together, these two functions allow us to summarize information by group. In the real world, we'd use this to see subtotals and category totals, which are essential in reporting and analysis.