I don’t know much about statics but looking at a boxplot there’s a minimum whisker to the left and a maximum whisker to the right. Then, there’s outliers laying outside of both whiskers.
If the minimum whisker marks the lowest value for the data, why are there values outside of the minimum or maximum whiskers?
In: Mathematics
Outliers are values so far away from the rest of the data that it’s not helpful to use them as the minimum or maximum values, so they are essentially ignored for the plot itself. Let’s say you wanted to weigh various small objects around your house. They mostly weigh a couple of pounds, and you even find one that weighs ten pounds. You make a boxplot of the data and it gives you a good idea of what the distribution looks like.
Then you remember you have a tungsten cube up on one of your shelves and it weighs over 40 pounds. If you included that in the max value whisker, then suddenly that whisker would be like 8 times longer and becomes functionally useless. The whisker is supposed to tell you where the upper 25% of values lie, but because of one single value, you’ve skewed the entire plot to make it look like most of that quartile is far above where those values actually fall. As such, it is far more informative to just say “yes, we technically have a 40lb object in our data, but most of our stuff is actually way down here in this whisker”
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