Friday, July 1, 2011

Experimental Design & Scatterplots (Coffee & Caffeine)

Nice little video on the story of coffee.

(h/t John D. Cook)

I did a little additional reading after the video. Here are some lesson ideas or activity that could be developed.
  • The first one is on LD50 or Median Lethal Dose.
    The LD50 or Median Lethal Dose of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration. LD50 figures are frequently used as a general indicator of a substance's acute toxicity. The test was created by J.W. Trevan in 1927.
    We could use the value from the video of 150mg/kg to create chart with weight of a person as the independent variable and dosage as the dependent variable. Sketch the graph and interpret the results. One extension would be to get students to select their favorite drink and find the caffeine content and do some additional activity with it. Even though the video explains there's no recorded deaths from caffeine overdose from drinks, I have some reservations about this since I'm working with teenagers.

    We could alternatively do a similar activity, but focus on rats instead of humans, grab the data from the table of LD50, which lists 192mg/kg (data from rats that were administered orally), to create a table and interpret results. We could also discuss about how this data would be obtained and why the Fixed Dose Procedure is being recommended as an alternative.
  • The second idea is to build off of the assertion in the video about caffeine's (coffee and tea) role in the Enlightenment. Discuss the possibility of alternative explanations such as coffee/tea houses bringing of people together in these "penny universities" in an alert state so that ideas can develop, spread, and flourish. Perhaps use this as an introduction to the lady tasting tea (there's a book with same name by David Salsburg, I won't link it here) and the birth of randomized experimental design by Sir Ronald Fisher.
  • The third idea is a more boneheaded extension of the above to achievement of students in international tests due to coffee consumption. Students would create a scatterplot from data about coffee consumption per capita and plot it against either TIMSS or PISA scores and interpret the results in context. What are some assumptions made? What conclusions can we draw? What are some possible confounding variables? Are there outliers? Which is a better predictor of achievement in these tests: GDP per capita or coffee consumption per capita?
  • The fourth idea is to discuss this little gem found by John D. Cook about why headache is often listed as a side effect in drugs. Be sure to also read the comments on his blog.
    In an interview on Biotech Nation, Gary Cupit made an offhand remark about why so many drugs list headache as a possible side-effect: clinical trial participants are often asked to abstain from coffee during the trial. That also explains why those who receive placebo often complain of headache as well.
    Use this as an opportunity to discuss experimental design.
  • The fifth idea is to discuss the flawed study about the link between coffee and lung cancer. The page at Google Books only gives a generic example, I was hoping to see an actual study referenced. The closest I can find after a bit of searching is this article about cancer myths. Maybe someone can point me in the right direction.
Comments, suggestions, and/or corrections are welcome.

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