Base Rate
Base Rate
[Cueball is standing in front of a screen that shows a bar graph with 2 bars with labels beneath. The right bar is significantly higher than the left. Cueball is holding a pointer which he points at the label of the highest bar, which has been encircled.] Cueball: Remember, right-handed people commit 90% of all base rate errors. Label: L R

The " base rate " is a type of base probability, which a statistical probability can be based on. The base rate fallacy is a type of error in which people are presented with the rate at which something occurs throughout an entire population along with more specific information about a subset of that population, and tend to ignore the whole-population information in favor of the specific information.
In this case, the joke is that 90% of people are right-handed, so if there is no connection between handedness and making base rate errors, then 90% of these errors would be made by right handers.  Thus while Cueball's claim that right-handers commit 90% of base-rate errors is technically true, taking that as reason to believe that "making base-rate errors" is somehow specially associated with right-handed-ness -- as would be implied by an intervention effort specific to right-handed-people -- is itself a base-rate error.
Cueball may be holding the pointer in his right hand, suggesting he might be right-handed (as 90% of stick figures are [ citation needed ] ).  Since Cueball has no facial features it is impossible to tell if he faces the audience, or looking at his graph. However, it seems most likely that he is looking at his audience while delivering the take home message and thus points at the graph behind him. Thus he likely belongs to the 90% that makes 90% of the base-rate errors, one of those he is just committing.
In the title text, Cueball dismisses the idea of adjusting his graph to account for the difference in numbers of left-handed versus right-handed members of the population.  He suggests focusing efforts on the right-handed majority to resolve that 90% of base rate errors.  This is a somewhat common counterargument to statistical arguments of this stripe (often as justification for racial profiling, for example); it fails because if the target group is not in fact somehow special with regard to the issue at hand, there is generally "nothing to fix" and no special approach to discover that cannot be just as easily applied to the population of the whole.
Something similar occurs in 1138: Heatmap , where Cueball makes inferences simply based on a population map of the US, instead of statistical evidence.
[Cueball is standing in front of a screen that shows a bar graph with 2 bars with labels beneath. The right bar is significantly higher than the left. Cueball is holding a pointer which he points at the label of the highest bar, which has been encircled.] Cueball: Remember, right-handed people commit 90% of all base rate errors. Label: L R
