Tag Archives: evolution

is this data significant?

26 Jul

If the word kurtosis brings to mind Grandma and a desperate need for Listerene, then we’re probably in the same boat when it comes to statistics. I love numbers, data, infographics, etc, but statistical tests have always challenged my patience intellect. For the longest time, I felt p values were like those magic eye paintings where you stare at them for awhile in frustration, and then when you finally glimpse a bit of what might be the image (is that a triceratops? sailboat?), you blink and the image vanishes.

magic eye image

magically annoying

Needless to say, this summer I bit the bullet and took a class in experimental design, methods, and stats as part of my masters degree. Totally changed my understanding of how statistics fit into science. I’ve still got plenty to learn, but I’ve resolved to take my newfound appreciation for statistical analysis and revamp my lab curriculum.

I mentioned in a previous post my recent change to teaching evolution first. One of the first lab activities I usually do is something to demonstrate the variation that exists in populations (e.g. measuring height/weight data in class, etc.).

I’ve taken this idea and created a scenario-based lab where students have to figure out a way to compare two populations. Here’s a snippet:

“Just the other day your boss, Pedro, was thanking you for saving the store money after you found a new local mealworm distributor offering cheaper prices. A few dead reptiles later, and your boss is threatening to fire you. He claims the new mealworms you ordered are different, and he’s blaming the new worms for his dead reptiles. And you thought all mealworms were created equal.

You need to design an experiment or experiments to determine if there is a significant difference in the two populations.

How will you ensure standardized data collection procedures? What outside factors might influence your data collection? How will you use the data you collect to make a comparison? How can you quantify the differences between the two populations (or lack thereof)?”

This of course leads into all sorts of interesting discussions related to statistics. This could be a little statistical appetizer or a whole can of worms, depending on the direction you want to go. By my count, at least three different statistical tests could be used to compare the samples, one of which barely requires any calculations (tukey’s quick test).

Like what you see? Download the whole shebang here: MealWormStats

(CORRECTION: Mann-Whitney U test actually compares the median values of two populations, not the mean and has been corrected in the file posted above.)

Feedback welcome.


in the beginning there was……science

22 Jul

My love affair with science goes back as far as I can remember, and it has relentlessly influenced my life since. It’s also the lens through which I view pretty much everything, this blog included. Now that I’ve gotten that off my chest, let the fun begin.

Speaking of beginnings, I’ve been thinking a lot about the start of this school year.  It’s no revelation that minute one, day one sets the stage for the rest of the year. I’ve always been a big believer in hitting the ground running, but this year I’m looking to take it up a notch. Here’s my day-to-day plan for this year:

  1. Provocative image/video showing on screen when students are walking in
  2. 1-2 questions as a lead in to the topic of the day/week/etc
  3. Take out writing instrument. Start writing. There is no wrong answer.

While a Mylie Cyrus photo tweet may qualify as provocative, not exactly what I’m going for here.

Here’s a preview of day one in AP Bio this year, opening the ecology unit:

I want to set the tone right from the start that it all starts with unexplained observations and the quest to find an explanation. How would we go about figuring out what’s going on here? What kind of experiments could we design to test our initial ideas? This is where I want to go all year long

Another sneak peak….Bio class day one, evolution and a video (sans audio) of a Devil’s garden (irony?):

We’re going down the evolution road, but first, what’s happening here? Next, how did we get here? No solutions yet – just discussion – we’re just whetting the appetite a bit. We’ve got plenty of Darwinian ground to cover first, but I we’ll get to that soon enough…

Note: Last year I decided to take the traditional micro to macro course sequence and turn it on its head. Why save the best for last? Let’s put evolution where it belongs, as the foundation that biology is built on.  Couldn’t be happier with the choice and looking forward to building (sorry…) on last year’s changes.