internal validity assignment finished
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Capella University *
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5002
Subject
Geology
Date
Dec 6, 2023
Type
docx
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2
Uploaded by AgentOtter2317
IDENTIFYING INTERNAL VALIDITY ISSUES
1.
An applied psychologist wants to test the effectiveness of an intervention to increase
awareness of the environmental impact of disposable water bottles. The initiative
involves asking students to use a smartphone to track the number of disposable water
bottles they use, categorizing whether they reuse them, throw them away, or recycle
them. He asks for volunteers in a large geology course. Students must own a smartphone
in order to participate in the intervention group. Fifty volunteers who owned a
smartphone were assigned to the tracking condition (they downloaded a free smartphone
app for this purpose). Fifty more students who were interested, but who did not own a
smartphone, made up the comparison group. This group was simply exposed to a short
video on the impact of plastic water bottles. At the end of a two- week period during
which the students in the smartphone group tracked their water bottle use, the researcher
found that students in the tracking program were more likely to have purchased a
reusable water bottle in the past week compared with the students in the comparison
group. He concluded that his smartphone tracking program raised awareness, causing
students to purchase reusable bottles.
Are there any internal validity issues? If so, describe the issue(s)?
The design of this study can be changed. The researcher should
conduct his experiment with a sample of students who have smart
phones. Doing this allows both groups, intervention, and
comparison, to own smartphones. There should be ONLY one
group that has the tracking app. Doing this will allow the results to
be compared without there being a cofounding variable. The
internal validity within the study will increase.
2.
A cognitive psychologist believes that people learn better when they spread out their
studying over several days, so she creates a study with three groups of participants. Each
group studies the same list of 120 Chinese vocabulary words (none of the participants had
studied Chinese before). One group studies the words for 20 minutes on the first day. The
second group studies the words for 20 minutes on the first and second days. The last
group studies the words for 20 minutes on the first, second, and third days. On the fourth
day, all of the participants are tested on how well they have learned the Chinese
vocabulary words. The people in the last group scored the best, so the researcher
concludes that distributed studying does improve people’s ability to learn.
Are there any internal validity issues? If so, describe the issue(s)?
This study is designed poorly. The third group will score better
than the other two groups that are in the study. This because the
third group was able to get more studying time and had time to
study before the test was passed out. This study can be redesigned
in a way that allow each group will get the same amount of
studying time.
3.
A human factors psychologist is comparing visibility features for automobiles. (Human
factors psychologists study how humans interact with the material world.) He plans to
test whether drivers will avoid obstacles behind their cars more effectively when the car
IDENTIFYING INTERNAL VALIDITY ISSUES
is equipped with an enhanced rear- view mirror, a rear video camera system, or an object
detector that sets off a buzzer alarm. He places a sample of 25 drivers into each of three
cars. The cars are identical except for their object detectors. The drivers spend 1 hour
familiarizing themselves with their vehicles and their object detectors by running through
a set of drills on a closed driver’s course. During a test phase, the researcher places a set
of objects behind each driver. The test objects range in height, color, and movement. Each
driver attempts to back up his or her car while avoiding each of the test objects. Each
object is presented three times each. The psychologist finds that, on average, drivers
respond more accurately to the rear camera video system compared to the rear-view
mirror or the buzzer alarm.
Are there any internal validity issues? If so, describe the issue(s)?
This study has some relevant issues of internal validity within the
group design. There are no details about how a group of 25 people
was selected or if they were choosing randomly or not. This can
cause some selection bias. There was also probably have been
some problems of practice due to the repeated tests using different
equipment. Each participate had to perform this test 3 times with 3
different machines. This will cause a strong inference that the
order that each participate partake in, had a strong influence on the
final outcome.
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