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| | ==Explanation== | | ==Explanation== |
| − | This comic deals with the faulty application of general statistics based on a large population, such as all Americans, to specific situations with vastly different statistics, such as astronauts.
| + | {{incomplete|Created by an ASTRONAUT STRUCK BY LIGHTNING. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}} |
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| − | A manned rocket ship is about to be launched into space. Mission control counts down from "T-minus 20," where "T" stands for the time at which the rocket is scheduled to launch. In the capsule, one astronaut asks another how they are feeling. The second admits that they are nervous. The first one offers a supposedly reassuring observation that they are more likely to be struck by lightning than to be selected to become an astronaut. Such comparisons are commonly used to illustrate that a particular probability is very small, and therefore not worth worrying about.
| + | This comic deals with statistics based on a large population, such as all Americans, when the people in question are in a smaller group with vastly different statistics, such as astronauts. |
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| − | The second astronaut is about to agree that they have a good point, but then realizes the problem with their argument: the likelihood of being ''selected as an astronaut'' is a moot point, because they both ''already'' '''''are''''' astronauts. The comparison ignores the relevant concern, which is the danger involved in ''being'' an astronaut and launching into space. It may also provoke a false understanding that, given two events each with given likelihoods of happening, where chance has proven sufficiently provident enough for the less likely one to have occurred, the 'luck threshold' has been exceeded enough to make the more likely one now a practical certainty (a variation upon the {{w|hot hand}} fallacy, though with nominally independent events and opposing desirabilities).
| + | In a capsule about to be launched into space, one astronaut asks another how they are feeling. The second one admits to feeling nervous. The first one offers the supposedly reassuring observation that he's more likely to be struck by lightning than to be selected as an astronaut. Such "more likely to be struck by lightning" comparisons are commonly used to illustrate that a particular risk is very remote, and thus should not be considered particularly frightening. |
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| − | The second astronaut's nervousness is understandable as space missions are historically quite dangerous, and have numerous avenues for potentially fatal failure, certainly far beyond the minuscule risk of being struck by lightning, approximately [https://www.weather.gov/safety/lightning-odds 1 in 14,600 throughout your entire life]. | + | The second one agrees with the first one for a moment, but then realizes that something is wrong with the argument. Presumably, he realizes that the likelihood of being ''selected as an astronaut'' is a moot point -- he's there because he ''already has'' been selected as an astronaut. The relevant concern is the risk level faced by an astronaut, given that he already holds that position. Unfortunately, the historical record shows that this risk is somewhat high, certainly far above the minuscule risk of being struck by lightning. |
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| − | The title text creates additional confusion by referencing another common statistical reference point, the probability of dying in a shark attack. In addition to shark attacks being uncommon, they are also less likely to kill their victim than is commonly assumed. Still, while shark attacks are more frequently fatal than rocket launches, this comparison is once again useless, as the astronaut is not in any danger of sharks, but is literal seconds from launching into space. The astronaut is presumably not especially reassured by the "pretty high" survival rate. | + | The lifetime odds of being struck by lightning are approximately 1 in 14,600.[How Dangerous is Lightning? https://www.weather.gov/safety/lightning-odds] |
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| − | Of the 557 people who who had been in Earth orbit (as of the time of this comic) 18 (3%) have died in related accidents, not specifically at launch ({{w|List of spaceflight-related accidents and incidents}}, [https://www.worldspaceflight.com/bios/stats.php Astronaut/Cosmonaut Statistics]). Of the 93 incidents logged for 2018 in the [http://www.sharkattackfile.net/index.htm Global Shark Attack File], 4 (4.3%) were fatal, but the statistic has been higher in the past when there was likely less education against provoking sharks.
| + | The title text refers to another common comparison, the risk of a shark attack. In addition to shark attacks being rather rare, they are also not as likely to kill the victim as is commonly assumed. Most people attacked by sharks, and most people launched into space, live through the experience; however, it remains true that both are considerably riskier than many if not most common activities.{{Citation needed}} |
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| − | A large metal rocket, such as depicted would be more likely to be struck by lightning than nearby structures. However launch controllers generally monitor weather carefully to reduce the chances of attempting to launch when lightning is likely. | + | A tall rocket, such as depicted would be more likely to be struck by lightning than nearby structures. However launch controllers monitor weather carefully to reduce the chances of attempting to launch when lightning is likely. |
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| − | A spacecraft launch can also trigger lightning, by creating a conductive path through electrically charged clouds. Apollo 12 was struck by lightning twice during the launch phase. Thankfully backup systems allowed the flight to proceed. For more information, see [https://www.nasa.gov/audience/foreducators/9-12/features/F_Lightning_and_Launches_9_12.html NASA: Lightning and Launches] | + | A space craft launch can trigger lightning, by creating a conductive path through charge bearing clouds, which would normally not produce lightning. Apollo 12 was struck by triggered lightning twice during launch phase, resulting in the entire operational platform shutting down from overload. Backup systems allowed the flight to proceed.[NASA: Lightning and Launches https://www.nasa.gov/audience/foreducators/9-12/features/F_Lightning_and_Launches_9_12.html] |
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| − | The perceived value of risk is a recurring topic and is also featured in [[795: Conditional Risk]] and [[1252: Increased Risk]].
| + | ==Transcript== |
| | + | {{incomplete transcript|Do NOT delete this tag too soon.}} |
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| − | ==Transcript==
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| − | :[A large spaceship rocket is standing on its launchpad, just decoupled from the tower that supports it ready for launch. At the very top of the rocket where the astronauts are sitting there are two lines coming out, indicating the speak from the two astronauts inside the rocket. Next to the top of the rocket there is a speech bubble drawn with jagged line indicating sound from a loudspeaker. It is the countdown to the launch.]
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| | :Astronaut 1: How you feeling? | | :Astronaut 1: How you feeling? |
| | :Astronaut 2: Honestly, pretty nervous. | | :Astronaut 2: Honestly, pretty nervous. |
| − | :Astronaut 1: I know it seems dangerous, but just remember: you're more likely to be struck by ''lightning'' than to be selected to become an astronaut. | + | :Astronaut 1: I know it seems dangerous, but just remember: you're more likely to be struck by lightning than to be selected to become an astronaut. |
| | :Astronaut 2: Oh that's a good- | | :Astronaut 2: Oh that's a good- |
| | :Astronaut 2: ...Wait. | | :Astronaut 2: ...Wait. |
| − | :Countdown: T-Minus 20...19... | + | :Background: 20...19... |
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| − | ==Trivia==
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| − | *During the time that this comic was on the front page of xkcd, the [[Design_of_xkcd.com#Header|Header text]] changed to [[Design_of_xkcd.com#2019-02-06|promote]] Randall's new book ''[[How To]]''.
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| − | **As this could also be seen as a launch (a book launch) with certain risks, there could be some relation to putting it up together with this comic.
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| | {{comic discussion}} | | {{comic discussion}} |
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| − | [[Category:Statistics]]
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| − | [[Category:Space]]
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| − | [[Category:Sharks]]
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