In the context of this lesson, what happens if there are outliers?
Outliers can happen in reality and are not always avoidable. In addition, unless there is a very good reason to remove them, outliers cannot be easily excluded from real-world data.
As a result, outliers can appear somewhat frequently in datasets. When there are outliers, they can have a fairly strong influence on the slope and intercept of the dataset. As a consequence, the line of best fit for the data can be slightly off, or possibly even completely wrong.