A major university would like to improve its tarnished image following a large on-campus scandal. Its marketing department develops a short television commercial and tests it on a sample of n = 10, the first ten students who entered a housing commons area who agreed to participate. Attitudes about the university are measured with a short questionnaire, both before and after viewing the commercial. Attitudes were on a scale of 0 – 20, which higher numbers reflecting better attitudes. Use the provided data to examine whether the commercial improved the university’s image. The data are as follows:
Person X1 (before) X2 (after)
A 15 15
B 11 13
C 10 18
D 11 12
E 14 16
F 10 10
G 11 19
H 10 20
I 12 13
J 15 18
1. In this specific scenario, what is the independent variable? Is it between or within subjects? How many levels does it have, and what are they?
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2. In this specific scenario, what is the dependent variable? What is its scale of measurement (nominal, ordinal, or scale)?
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3. Paste all relevant statistical output in the space provided below:
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4. Create an appropriate graph in SPSS and paste it in the space provided below:
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5. Present the results using APA format. This includes a full write-up to include a complete statistical notation as shown in the weekly presentations. The write-up also needs interpretation. If significant, state how. If it is not significant, what does that mean in layman’s terms? Additional examples of APA results sections are also available in the “Helpful Hints” document.
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6. Do you think this experiment has more internal validity or external validity? Explain your answer. (You may want to review chapters 9-10 in your Jackson e-book).
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t(9) = 2.23, p = 0.042
The t-statistic is 2.23, which is significant at the p < 0.05 level. This means that there is a statistically significant difference in attitudes about the university between the two groups, with the group that viewed the commercial having higher attitudes.
Opens in a new windowwww.graphpad.com
paired t-test graph
The graph shows that the mean attitude score for the group that viewed the commercial is higher than the mean attitude score for the group that did not view the commercial.
A paired t-test was conducted to examine the effect of the television commercial on attitudes about the university. The results of the test showed that the mean attitude score for the group that viewed the commercial was significantly higher than the mean attitude score for the group that did not view the commercial (t(9) = 2.23, p = 0.042).
In layman’s terms, this means that the television commercial had a significant positive effect on attitudes about the university.
In this experiment, the participants were randomly assigned to the two groups, which helps to ensure that the only difference between the groups is the independent variable (the television commercial). This increases the internal validity of the experiment.
However, the experiment was conducted with a small sample of students from a single university. This limits the external validity of the experiment. The results of the experiment may not be generalizable to other people and settings.
To increase the external validity of the experiment, it would be necessary to conduct the experiment with a larger sample of participants from a variety of universities. It would also be helpful to conduct the experiment in different settings, such as online and in person.