Control Groups in Experiments

Comic strip on Control Groups in Experiments

xkcd – Control Groups in Experiments


  • My hobby: sneaking into experiments and giving LSD to the control group
  • Control group member 1: My rash seems to have shrunk by about 20% today.
  • Control group member 2: OH GOD SPIDERS!


  • to sneak into (v.) /sniːk/ to go quietly somewhere  you are not supposed to go without anyone noticing you
  • experiment (n.) /ɪkˈsperɪmənt/  a test, especially a scientific one, that you do in order to learn something or discover if something is true
  • LSD /ˌel.esˈdiː/ an illegal drug that causes people who use it to see the world differently from the way it really is or to see things that do not really exist
  • control group (n.) a group of people who are used for comparing another group to in a test or experiment
  • rash (n.) /ræʃ/ a lot of small red spots on the skin
  • to shrink (v.) /ʃrɪŋk/ (irregular verb: shrink, shrank, shrunk) to become smaller, or to make something smaller:


  • To understand this comic, you need to understand who is who in the picture:
    • The 2 people on the left are the researchers who are conducting an experiment.
    • The 2 people on the right are people from the control group in the researchers’ experiment.
  • You also need to know that when researchers conduct experiments, they apply what they are studying on one group of people (often called the experimental group, test group, or treatment group), then they compare the results with the control group (i.e. = people who are supposed to be normal). That way, they can study the differences between the people who were affected by the experiment and those who supposedly shouldn’t.
  • What is funny here is that the author gave some LSD to the control group (without anyone noticing it), so the control group is not normal anymore and behaves in a very strange way. Now, you can understand why the researchers are very confused as to why they behave like this!

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