12: Poisson

Explain xkcd: It's 'cause you're dumb.
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Image Text

Poisson distributions have no value over negative numbers


In this comic, Cueball expresses himself as a Poisson distribution.

In mathematics, a Poisson distribution is a distribution that shows the probability of a given number of events occurring in a fixed interval of time or space (wiki!). Along the horizontal axis is typically the “number of events” while the vertical axis is a decimal representing the probability (i.e. 0.5 for 50% probability). It is commonly represented by a bar graph, or a point graph (sometimes with a line connection to show a trend, even though there is no actual value for non-integers).

A simple example is the number of heads coming up on a fair coin flip. With one coin flip the distribution should be 0.5 at 0 heads and 0.5 at 1 heads. For 2 coin flips, the distribution would be 0.25 at 0 heads, 0.5 at 1 heads and 0.25 at 2 heads. Etc. multiple graphs like this are sometimes overlaid on one graph with a legend to distinguish the points (one coin flip in red, two coin flips in blue, etc).

Note that this distribution only has data points on non-negative integers and is not continuous through decimal numbers or (as the image text tells us) negative numbers because events can’t occur 0.3 of a time, or -2 times.

After implying that the concept of a person being a mathematical distribution is irrational, Black Hat suggests he is “less than zero”. Since the Poisson Distribution doesn’t exist or has no value at negative values, Cueball either leaves or disappears magically.

Hence, the punchline is the same as the image text: Cueball doesn't exist to Black Hat anymore, because he has a value less than zero.


- This is the first appearance of Black Hat in the comic. - Randall was still experimenting, as Cueball still has a face in the first two frames.