Exercise

Summarizing by year

The summarize() function is especially useful because it can be used within groups.

For example, you might like to know how much the average "agreeableness" of countries changed from year to year. To examine this, you can use group_by() to perform your summary not for the entire dataset, but within each year.

Instructions

100 XP

Add a group_by() to your code to summarize() within each year.