Sampling bias example via NASA, Pew Research Center, and Twitter

Today's post is one, small, to-the-point example of sampling bias.

On May 27, 2020, my family and I were awaiting lift-off for the (subsequently grounded) NASA/SpaceX launch. To no one's surprise, I was following NASA on Twitter during the hoopla, and I noticed this Tweet:

https://twitter.com/NASA/status/1265724481009594369

And I couldn't help but think: That is some sampling bias. Admittedly, their sample size is very impressive, with over 54K votes. But this poll went out to a bunch of people who love NASA so much that they follow it on Twitter. 

What is a less biased response to this question? As always, Pew Research Center had my back. 58% of Americans responded that they definitely/probably weren't interested in traveling into space:

https://www.pewresearch.org/fact-tank/2018/06/07/space-tourism-majority-of-americans-say-they-wouldnt-be-interested/

If you want to expand upon this example in class, you could ask your students to Google around for information on the typical Twitter user and whether or not they are representative of the average American. You could also go to the link for the survey and learn more about the exact methodology used by Pew research to gather their data. 

The Washington Post's "The coronavirus pandemic and loss of aircraft data are taking a toll on weather forecasting"

The Washington Post, and numerous other media outlets, recent wrote about an unintended consequence of COVID-19 and the sudden drop off in commercial flights: Fewer data points for weather forecasts (PDF).

Due to the coronavirus, commercial flights are down:

How does this affect weather forecasts? Data is constantly being collected from commercial flights, and that data is used to predict future weather:

Ways to use in class:

A conceptual example of multivariate modeling: Windspeed...temperature...humidity...lots of different data points, from lots of different elevations, come into play when making our best guess at the weather. This is a non-math, abstract way to discuss such multivariate models.

A conceptual example of effect sizes/real-world effects: In the article, they clearly spell out the magnitude of the data loss. That is pretty easy to track since we can count the number of flights that have been canceled. More complex is determining the effect size of this data loss. 

Data in everyday life: Per my introduction, we use weather forecasts for many different reasons. 

Control groups and alternate means of data collection: The article also contains excerpts of an interview data scientists who are trying to understand the magnitude of the issue AND solve it. Specifically, they stated that it is difficult to gauge the overall impact of the lack of data because they don't have a true control group (a nice example for RM) AND that they have come up with an alternative way of collecting high-altitude data: Good old weather balloons. This a good example of how a bit of expertise and creative thinking can be used to solve problems. 

Using the GroupMe App to encourage syncronous and asyncronous conversations with distant learners

Hi! This post is a change of pace. Instead of providing an example to use in stats class, I'm going to share how I incorporated text-message based class discussion in online courses with the GroupMe App. Doing so was a big win for me during a hard semester, I hope it is a big win for anyone who happens to read this post and use GroupMe in the future.

My experience using GroupMe App to facilitate class discussion during The Rona

My goals for OL SP20: I wanted my students to learn. I wanted to preserve the best parts of my classes. I didn't want my classes to be another burden in a stressed out world.

During March 2020, I wast teaching Introduction to I/O Psychology. It was a class of 20. My students were mostly Juniors and Seniors, who were either psychology majors or minors. On our last day of f2f class, when we knew that we were going to transition to OL, I asked my students to reserve our normal 12:20-1:25 MWF meeting time for the class.

I wanted my students to continue to have substantial in-class discussions. At the beginning of the semester, my students had divided themselves into consulting firms (hey, it was I/O) for small group activities and discussions throughout the semester. I wanted to maintain those consulting firms and those friendships among my students. Classroom interactions give them the ability to share personal experiences and apply theory to their own lives. It lets them articulate their thoughts about class materials. They had the opportunity to learn, clarify their thinking, and debate with the other members of their consulting firms. I wanted my students to have that in some virtual format. 

I also wanted my classes to be mostly synchronous.  However, I wanted to provide flexibility for students who are essential employees, de factor babysitters for younger siblings/nieces/nephews, parents, etc. So I needed a manner of interaction that could happen in realtime, but could also accommodate students who just couldn't show up at the scheduled time.

Traditional LMS discussion boards would work. I believe that most discussion boards hosted my LMS (in my case, Blackboard) are a bit clunky. They might be useful if students need to post more extended reactions to a prompt, but I don't think they encourage a real back-and-forth dialog among students. 

Why I went with GroupMe and not other discussion mediums: Text-based, low bandwidth, accessible via a phone.

I think Zoom is perfect for some things and not so good for other things. For me, I didn't think it would work for what I was trying to accomplish in my classes. Just because a typical f2f seminar class involves a bunch of students staring at you while you talk doesn't mean we should mimic that experience when lecturing virtually. 

I decided to behave as if my students would have financial and technology limits. I was also concerned with the technology available to my students while they were home. I didn't want to burden my students with RAM-heavy, bandwidth-heavy Apps, or programs, especially if they were doing most of their work via phone or tablet. I didn't want to force them to share a video stream of themselves and their homes, either. 

They know how to communicate via text messages. I also thought about how humans use cell phones to communicate. Almost all of us text and text a lot. I'm 20 years older than my students, and I have a 10-year-old group text conversation with my dearest friends from graduate school. My 71-year-old mother and I text frequently. Our students are effective text communicators. 

As such, I went with GroupMe, a text-based (with some frills) App that can work via cell phone or web browser. Anyone can download the App, start a group, and invite others to join the group. For my I/O class, I had one main class group, and then I asked my students to create (and invite me to join) smaller groups for their consulting firms. I asked that my students use avatars that are recent photos and include their actual names as their usernames. I asked my students to have the App open/available during our standard class times. 

How I incorporated GroupMe into pre-recorded Powerpoint lectures

For every day of class, I would create a Powerpoint and then generate a voice-over video of the Powerpoint using Kaltura. My presentations were usually 30-40 minutes for my 55-minute class to allow time for class discussion without running over. 

So, my students would view a Kaltura video. Some days, it was a traditional lecture. Other days, I would ask them to read a short popular news article, a research article, or watch a brief YouTube video. For example, one day, we covered different kinds of leadership behaviors as described by the Path-Goal Theory.

After covering the topic, I would ask my students to pause the Kaltura video and head over to GroupMe for a brief, small group discussion:

And they would go have discussions. They would chat, staying mostly on topic. They would wait for their classmates to catch up and pace themselves. I would chime in. I would sometimes go in and tell them to go back to the Kaltura video. Occasionally, a student would post to the GroupMe a few hours after the class "met" and apologize for not participating because other responsibilities got in the way. In those instances, the students were good at responding to the GroupMe prompts on their own, and one or two group members would typically respond to the asynchronous comments. 

Here is one such discussion from the Flat Earth Consulting Corporation about emotions in the workplace. Yes, the name of their group is a joke.

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What I really liked about GroupMe:

1. You can "see" your students in-class without apps like Zoom, which require more bandwidth, a functioning camera (if you insist upon it).

2. It is free.

3. You can set up individual chat groups in GroupMe, for both your entire class or for small groups. If you make yourself a member of each smaller group, you can jump in and out of small group discussions to keep things on track, comment, etc. Honestly, you can probably monitor and participate in your students' small group discussions better in this App then you could in real life. 

4. You can use GroupMe on a smart device or on your desktop. I used it exclusively on my desktop.

5. You can do class polls, share photos, share documents, people can "Like" one another's comments, you can tag a specific participant if you are replying to one of their comments.

6. Student feedback. They participated. All of them. For the remainder of the semester. Also:

Obvs, this isn't formal evaluation data. But these comments were shared spontaneously and "Liked" multiple times. 

Things to consider if you use GroupMe:

1. Is this an Official Mode of Communication between you and your students?

Anyone in GroupMe can send you a private message. I had students messaging me directly with questions about homework assignments, reminders to post homework assignments, etc. I am fine with this, but you may prefer to strictly use your email for this purpose. Also, you should probably adjust the Notification for the App accordingly.

2. If you track your attendance via GroupMe, consider using the Poll feature or a link to your LMS.

Per the description above, I used GroupMe participation for attendance points. This meant that I had to scroll through the GroupMe interface, checking off students for participation. That took a while, and it would be time prohibitive if you have 100 students broken down into 20 chats. How to avoid this? During the conversation, you could create a Google Form for students to jump into to generate a spreadsheet that shows attendance. Another option would be to share a link to an LMS assignment (I did that often) within GroupMe.