Median-Median Line

[lhawkins@urbanschool.org]

Is there a way for CODAP to automatically graph the Median-Median line?

Related, is there a way to plot two values on a graph? In Fathom, I had an activity that plotted the 33rd and 67th percentile, to have students eyeball the Median-Median line (which we had just learned to do on paper). And then we would click on Fathom’s Median-Median line tool and see how it compares.

[Bill Finzer]

• There is no affordance in CODAP for plotting a median median line on a scatterplot. You’re the first to ask about it. How important do you think it is?
• You’re not the first to want to plot more than one value. It’s on our list of desired features.

Thanks very much for helping us prioritize feature development!

Bill

[lhawkins@urbanschool.org]

For our course (non-AP/honors Statistics & Probability), it’s been pretty key to our unit on 2-D data. Essentially, we look at 1-D data, talking about how different representations are useful for different types/distributions of data. Then we look at 2-D data, and compare Median-Median vs Least Squares lines. It helps them get a sense of how there are different tools for different types of data, especially regarding the role of outliers – which we’re trying to continue to develop number sense with. And it continues the thread of being critical of media representation of data – why did they choose this model? how does it further their goals in presenting this information?

Remote school has meant that we have to cut content, and not having this tool this year (since the kids’ laptops all just got updated to not have Fathom) is actually making me change what content I’ll be cutting for this course. Not having two choices for models for linear 2-D data takes out some of the critical thinking and makes it more procedural (make a line & interpret slope & y-int) once they understand how r^2 is calculated.

It’s not tragic, since I liked the content I ended up cutting out in the Spring (just because it fell at the end of the course & we didn’t get there), so I don’t really mind switching that around this year. But when we are, at some point, back to regular in-person classes, I would really love to be able to have them create a Median-Median line. I can teach Median-Median by hand like I did before, but without the technology to create one automatically, we can’t really use it for their researched data sets & project.

And there might be other tools that would work – I only took one basic Stats course in college and inherited this course at the high school where I teach, so Fathom was all I knew – but I’ve loved Fathom and I was so excited to find out about CODAP at the CMC North conference in 2019!

Thank you so much for your time!

Laura

[Bill Finzer]

Hi Laura,

Thanks for your detailed response. It really helps us think about how to prioritize the median-median line as a CODAP feature.

Bill

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