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Exercise

Finding outliers using IQR

Interquartile range, or IQR, is another way of measuring spread that's less influenced by outliers. IQR is also often used to find outliers. If a value is less than \(\text{Q1} - 1.5 \times \text{IQR}\) or greater than \(\text{Q3} + 1.5 \times \text{IQR}\), it's considered an outlier. In fact, this is how the lengths of the whiskers in a ggplot2 box plot are calculated.

Diagram of a box plot showing median, quartiles, and outliers

In this exercise, you'll calculate IQR and use it to find some outliers. Both dplyr and ggplot2 libraries are loaded and food_consumption is available.

Instructions 1/3

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  • Compute the first and third quartiles of co2_emission in food_consumption and store these as q1 and q3.
  • Calculate the interquartile range (IQR) of co2_emission and store it as iqr.