Quasi- Experiments

  1. Researchers Owens, Belon, & Moss (2010) wanted to investigate the impact of school start time on the sleep patterns of adolescents. They studied teenagers who were enrolled in an American high school, both before (fall semester) and after (spring semester) the entire school had decided to shift its start time from 8:00 am to 8:30 am. Students completed a survey asking what time they went to bed the night before, how many hours of sleep they’d gotten, and their daytime sleepiness and level of depressed mood. The researchers found that after the 8:30 start time was implemented, students reported getting 45 minutes more sleep each night, and the percentage of students who reported more than 8 hours per night jumped from 16.4% to 54.7%. In addition, students level of daytime sleepiness and depressed mood decreased after the 8:30 start time began.
    1. Is this study a nonequivalent control group design, a nonequivalent control group pretest/posttest design, an interrupted time-series design, or a nonequivalent control group interrupted time-series design?
    2. Graph the results of the study, according to the results in the description. (There are multiple dependent variables; choose only one to graph).
    3. What causal statement might the researchers be trying to make, if any? Is it appropriate? Use the results and design to interrogate the study internal validity
    4. If you notice any internal validity flaws, can you redesign the study to remove the flaw?
    5. Ask one question to address construct validity and one to address external validity.