Podcasts have been gaining in popularity in the last few years, and several feature psychological research. I'm going to be devoting my next few posts to some podcasts. We'll start with this very short, 3-minute episode/ interview from the NPR podcast, Hidden Brain. The episode is called "How does the way you feel shape your life?" and it's about how students might be influenced by situational factors (such as how early a class is) when they select their majors.
The podcast opens with a story:
...behavioral economist Kareem Haggag at Carnegie Mellon University... sometimes teaches early morning classes. And he's worried that when his students are tired or sleepy, they might draw the wrong conclusion about him and about the class.
The researcher himself states (around minute 1)
DR. KAREEM HAGGAG: Our hypothesis was that students who are assigned to an early morning section of the class, or to multiple back-to-back classes before a class, might mix up how tired they are in that class with how much they like the subject, thus leading them to be less likely to choose the subject as their major.
The host, Shankar Vedantam, reports:
This is a psychological phenomenon called misattribution. You know, you go to an amusement park on a sunny day and you think the park is great. You go when it's raining - you think the park is terrible. You're unconsciously confusing your feelings about the weather for the quality of the park.
The researchers used thousands of data points from students at the U.S. Military Academy at West Point to test their hypothesis. As Vedantam points out:
... students at West Point are randomly assigned classes that are scheduled at different times of the day, which means that some students are taking this introductory class first thing in the morning. Some students are taking the very same class later in the day. The researchers then measure the chance that students would later on choose that subject as their college major.
The researchers, led by Dr. Haggag, found that students were more likely to major in the topic of that introductory class if they'd taken it at a later time of the day:
HAGGAG: We find that students who are randomly assigned to the first period, 7:30 a.m. section, are about 10% less likely to choose the corresponding major compared to a student who takes that class later in the day.
Questions
a) What are the two main variables of interest in this study (the independent and dependent variables)? What are the levels of each variable?
b) Is this a true experiment or a quasi-experiment? If it's a true experiment, what kind is it (prettest-posttest, posttest-only, repeated measures, concurrent measures)?
If it's a quasi-experiment, which of the four types is it (nonequivalent control groups, nonequivalent control group prettest-posttest, nonequivalent control groups interrupted time series, nonequivalent control groups interrupted time series)?
c) Which is the IV and which is the DV here?
d) Sketch a small bar graph of the results they describe.
e) Can these researchers support the causal claim that "having an early morning introductory class makes you less likely to want to major in that discipline?" Apply the three rules of causation: covariance, temporal precedence, and internal validity in your response.
f) Ask a question about this study's internal, external, statistical, and construct validity.
Bonus content:
In the study above, the main IV was "time of day of the introductory class". As a bonus, here is another independent variable they studied--"number of breaks before the introductory class":
DR. KAREEM HAGGAG: We also compared two students who are sitting in the exact same classroom, but one of whom just had a free period as a break before, and the other came from one or more back-to-back classes. We find that each additional back-to-back class reduces the likelihood that that student enrolls in the major by about 12%.
g) Which is the IV and which is the DV here?
h) Sketch a small bar graph of the results they describe.
i) Can these researchers support the causal claim that "having breaks before your introductory class makes you more likely to want to major in that discipline?" Apply the three rules of causation: covariance, temporal precedence, and internal validity.
