How do you find the limit of outliers in box and whisker plot?

Answer 1

To find the limits of outliers in box and whisker plots, you first must determine the Interquartile Range. The Interquartile Range is the difference between the Upper Quartile and the Lower Quartile. For instance, if my Upper Quartile = 87 and my Lower Quartile is 52, then 87 - 52= 35. 35 is the Interquartile Range (IQR).

Next, you use the formula 1.5 x IQR to determine if you have any outliers.

Example:

1.5 x 35 = 52.5

Now determine the limit for the Upper Quartile by adding 52.5 to the Upper Quartile.

Example:

52.5 + 87 = 139.5

139.5 is the limit for the Upper Quartile.

Next, determine the limit for the Lower Quartile by subtracting the Lower Quartile from 52.5

Example

52 - 52.5 = -0.5

-0.5 is the limit for the Lower Quartile

Thus, the LIMITS are -0.5 and 139.5. In order for a number to be considered an outlier, it must either be less than -0.5 or greater than 139.5