985: Percentage Points
Cueball is watching a news story about a (fictional) Senator Grayton and his campaign for the then-upcoming 2012 election. After a series of absurd statements Grayton has lost a substantial number of prospective voters, but the news anchor's failure to specify between percentage and percentage points causes a little ambiguity that gets on Randall's nerves.
Senator Grayton is a fictional character, made up for this comic; which is unusual for xkcd, as it typically uses real-world references (indeed, three real-world names are mentioned in the title text). Given the frankly absurd, and in some cases illegal nature of Grayton's campaign promises, using a fictional character was probably necessary to avoid defaming any real world politicians.
The issues that Grayton supports:
- Tax breaks for drunk drivers: Grayton proposes giving those who have been convicted of a DUI or DWI (i.e. Driving Under the Influence or Driving While Intoxicated) money back on their taxes, when those infractions are typically severely penalized, as drunk driving has resulted in numerous deaths.
- Predator drones and the War on Christmas: The War on Christmas is not a real war; it is simply the perception by some Christians that non-Christians are trying to replace traditional Christmas imagery with more inclusive and generic holiday customs. No politicians have explicitly announced their support of the "War on Christmas," and the idea that one would not only do so, but would also want to use drones—ostensibly to harm or possibly kill people—in the effort is an absurd exaggeration of a relatively harmless culture war.
The term percentage point is used to overcome an ambiguity when comparing two percentages.
Reduction of a stated number by a percentage
- When the original value is given as a number, there is no ambiguity. If that 20% were of a sample size of 1 million, the starting number could be directly stated at 200,000. And thus, in the statement below, the only possible conclusion is that now only 162,000 people (81%, i.e. 100% minus that 19%, of the 200,000) approve of Grayton.
- Previously 200,000 people approved of Senator Grayton, and then his approval rating dropped by 19%.
Reduction of a percentage by a percentage
- When the original approval rating is given as a percentage (20% in the comic), then a reduction of 19% has two possible meanings:
- 1) Of the 20% who previously approved (200,000 people), 19% of those no longer approve. In this case the result is 162,000 as in the above example.
- 2) Compared to the original results, 19% fewer of the entire original sample approve. In this case only 1% of the 1 million now approve, equal to 10,000 people.
If using the second method of comparing percentages, the approvals rating should be described as having dropped by 19 percentage points. In reality, the distinction between the two methods is often overlooked, leading to confusion.
The caption's issue with "percentage" versus "percentage points" is that if Grayton's 20% approval rating drops by 19%, that means that his support has only dropped 3.8 percentage points since 19% of 20% is only 3.8%. That would mean that even after all his outrageous statements, his support dropped only from 20% to 16.2%. However, if the news reports that his 20% approval rating dropped 19 percentage points, that means his support has dropped to 1%, which appears to be more accurate given Grayton's egregious policy decisions and the description of his campaign as having "imploded."
The punchline to all this is that Randall is more bothered by the "percent" ambiguity than by Grayton's appalling policy plans.
References in the title text:
- Tracy Morgan is an actor who plays Tracy Jordan in the TV Show 30 Rock. He has been reprimanded for controversial comments on homosexuals and Sarah Palin (in separate incidents).
- John Wilkes Booth is the person who assassinated Abraham Lincoln. He was a Confederate sympathizer and supported slavery. The mention of his ghost could also be a reference to King Falls AM, an audio drama which features his ghost multiple times.
- "The Time Cube Guy" would be Otis Eugene "Gene" Ray. To put things very politely (as Mr. Ray was a very angry man with severe schizophrenia), he created a website known as Time Cube where he set out his personal model of reality, which he called Time Cube. He suggested that all of modern physics is wrong, in addition to claiming that religion is evil, specifically Christianity, and that the idea of family is poisoning children. Ray passed away in 2015.
- College scholarships to sexually active teens: Many people think adolescents should not engage in sexual activity, let alone be encouraged to do so by college scholarships. This is the opposite of abstinence programs, which encourage teens not to be sexually active until marriage.
- Illegal immigrants who create room for themselves by killing a citizen: Illegal immigration is a highly controversial topic in the United States. One argument against illegal immigration is that illegal immigrants are taking jobs away from American citizens. Proponents of immigration assert that this is not the case, since more people in the overall economy creates jobs and brings in more tax revenue. Neither group would be in favor of illegal immigrants murdering citizens even though it would cause no net gain or loss in population.
- Graduated income tax based on penis size: Many people are sensitive about their penis size and would probably consider the measurement of their penises for tax assessment purposes an enormous embarrassment and invasion of privacy. Even the scenario in which those with relatively smaller penises would be levied less tax than those with larger penises would probably not be sufficient for them to accept this policy, and even if they did, those with larger penises would probably consider this policy to be unfair. And the alternative—a scenario in which larger penises pay less taxes—would be both unfair and incredibly demeaning. Additionally, it is also entirely unclear as to how tax laws would apply to anyone without a penis in this scenario.
- [Cueball is sitting in an armchair watching TV while listening to a news report coming from the TV as shown by a zigzag line.]
- Voice from TV: Senator Grayton's campaign has imploded following the candidate's promise to give tax breaks to drunk drivers and to authorize the use of unmanned Predator drones in the War On Christmas. Grayton had been polling at 20%, but his support has since plunged by 19%.
- [Caption below the panel:]
- I hate the ambiguity created when people don't distinguish between percentages and percentage points.
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