Great! Every data analysis process has multiple phases.

First, explore your data to get to know and get accustomed to the dataset you'll be working with. You can do this in R, as in the previous exercise.

The next phase is checking the quality of data. Some data may be missing; some data may be erroneously entered. If you discover missing or incorrect data, you may try to repair it. We'll briefly talk how you can repair missing data later in the course. Technically, in order to fix your data, you need to know how to add new columns or modify existing ones.

Finally, you may want to add new features (variables) to make your analysis easier. Technically, that also involves adding or modifying existing columns.

In this part of the course, we'll primarily learn how to add new columns to a data frame and modify them.