Box Plot
Box Plot
[A box plot with three vertical data points is shown. Each point consists of a shaded rectangular box, and a T-shaped whisker on each end.]
[Cueball walks in; revealing that the box plot is a physical object which he looks up on.]
[Cueball climbs on top of the diagram, holding onto the top whisker of the leftmost data point.]
[Cueball, now standing upright on top of the box plot, bends over, grips the whisker of the center data point and starts pumping. The shaded box of the data point bulges. Cueball's movements are accompanied by sounds:] Pump Pump Pump
[The box has been inflated so much that it almost touches the left and right data points. Cueball walks away.]


This comic shows three vertical box plots in the first panel, hence the title.
In descriptive statistics , a box plot is a convenient way of graphically depicting groups of numerical data through their quartiles . The second quartile is the median and it is not indicated in this comic, as it should be a line through the box (see the definitions of quartiles ). But the top and bottom of the box is the first and third quartile, which splits the lowest/highest 25% off data of from the highest/lowest 75%, respectively.
Box plots may also have lines extending vertically from the boxes (whiskers) indicating variability outside the upper and lower quartiles, (that is, the highest and lowest values in the data,) hence the terms box-and-whisker plot. These can be used to indicate the interquartile range , a measure of statistical dispersion . These have been included on the three boxes in the plot.
The joke in the comic arises, because it turns out that the box plot is actually three real world objects and Cueball walks into the plot in the second panel, climbs up on the lower first box and on to the highest middle box. When the boxes are depicted in the orientation shown, the boxes can look like they are pumps, where the middle part, the box, can be pumped up. And Cueball does just that in the fourth panel, by pushing the top whisker down and when he leaves in the fifth and last panel, this box stays inflated, with the whisker visibly lower than in the first three panels, although higher than when he pushed it down in the fourth panel. (Inflating things that cannot be inflated was also the joke in 1395: Power Cord . But as opposed to inflating the meaning of data, which many researchers sadly do in the real world, what Beret Guy does in that comic, is strictly supernatural .)
It could be said that the "data" in this comic was "inflated" and thus Cueball has been trying to show a smaller interquartile range than there actually is, thus inflating the possible conclusions that could be drawn from the data.
The title text refers to how dynamite , an explosive, often used to have detonator boxes (aka. blasting machines ) which also looked similar to the top part of the box (without the lower whisker). These detonators were most commonly used for mining, with long wires leading to the explosives. Modern blasting machines are operated by push buttons and key switches, but the old push-handle design still resonates in the public consciousness today, due to its exposure in classic slapstick cartoon shorts like Looney Tunes , especially often used by Wile E. Coyote against the Road Runner. See this compilation for examples.
The title text also refers to so-called dynamite plots . This type of plot used to be very common in scientific publications, but since it hides most details about one's actual data, it is now frowned upon. The recommended alternative is the box plot.
The title text thus warns against this kind of data inflation, since sometimes it can go awry and lead to explosions. Randall has often made comics about presenting data as more important that they are, in one way or another, and this comics clearly falls into that category. See for example 882: Significant , 1132: Frequentists vs. Bayesians , 1478: P-Values and 1574: Trouble for Science , and this one for manipulating the way data is presented: 558: 1000 Times .
A box plot was also used in 539: Boyfriend , maybe the only other time in xkcd. There are many other types of data carts that have their own subcategories, but not this type.
[A box plot with three vertical data points is shown. Each point consists of a shaded rectangular box, and a T-shaped whisker on each end.]
[Cueball walks in; revealing that the box plot is a physical object which he looks up on.]
[Cueball climbs on top of the diagram, holding onto the top whisker of the leftmost data point.]
[Cueball, now standing upright on top of the box plot, bends over, grips the whisker of the center data point and starts pumping. The shaded box of the data point bulges. Cueball's movements are accompanied by sounds:] Pump Pump Pump
[The box has been inflated so much that it almost touches the left and right data points. Cueball walks away.]

