### See the complete Devil’s Dictionary of Scientific Words and Phrases here.

**anterior **the part of the body above the **posterior**, provided you have access to gravity, and are not standing on your head. Otherwise, place your hands on your posterior; the anterior end is everything in the opposite direction.

**posterior **if you are sitting down, what you’re sitting on; otherwise, what you would be sitting on, and everything below it. The posterior is also the part of a person that you have to ask your spouse whether it is getting too fat.

**ventral **the part of an organism that expands in direct proportion to the amount of beer that is consumed.

**dorsal **the region of a person that is opposite the **ventral** side; the part you can’t scratch or see without access to a mirror. If the ventral side is the side of a hotdog you put mustard and horseradish on, the dorsal side is the part near the bun.

**p value** *In statistics*, the p value is a number which indicates whether life is a sequence of random events with no meaning, or whether the universe really is out to get you. The p value can be useful when an experiment doesn’t work and you must decide whether to repeat it. While it may work the second time around, there’s always a risk that the results might turn out even worse; you might, for example, acidentally create some antimatter. Even if you created only a tiny little amount, hardly anything at all, not even a dollop, it doesn’t take much to cause the solar system to implode. Since this has never happened before, it’s hard to estimate the probability that it will on any given day. The p-value might hover at around 0.03 for weeks or months, and then suddenly, within just a few minutes, jump into the millions. If you’ve ever seen it happen, it’s pretty impressive. In general, scientists try to keep the p value for undesirable things as low as they can and raise it as high as possible for things they would like to happen. This is possible because the probability of the bad thing is often almost exactly the inverse of the probability of something good. In figuring the p value, put in any quantitative information that might be relevant.

As an exercise, estimate the p value of a zombie apocalypse. Here the only quantitative value you really need to determine is the *maximum number of days that it might take until the zombie apocalypse occurs, *which is probably the total number of days left before the sun expends all its energy, providing scientists are unable to develop a zombie apocalypse inhibitor beforehand. Since scientists place the future lifespan of the sun at about five billion years, the likelihood that a zombie apocalypse will occur on any given day is 5 billion x 365.4 (1,827,000,000,000). So the p value will be p = 1/1,827,000,000,000. Remember that tomorrow you will need to recalculate; tomorrow the p value will be 1/1,826,999,999,999. (Note, if your experiment involves antimatter, there won’t be any days left before the zombie apocalypse occurs, so p = 1/0; this is an irrational number, but you won’t be around to worry about it.)

*In clinical science*, the p value represents the amount a clinic will pay you for a warm cup of urine, or charge you for it, depending on whether they are asking you for the urine or you are asking them to take it from you.

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