In: Statistics and Probability
Research Scenario A
A psychologist is interested in the relationship between color of food and appetite. To explore this relationship, the researcher bakes small cookies with icing of one of three different colors (green, red, or blue). The researcher offers cookies to subjects while they are performing a boring task. Each subject is run individually under the same conditions, except for the color of the icing on the cookies that are available. Six subjects are randomly assigned to each color. The number of cookies consumed by each subject during the 30-minute session is shown in the following table:
Green |
Red |
Blue |
3 |
4 |
6 |
5 |
2 |
9 |
5 |
5 |
4 |
6 |
3 |
7 |
2 |
4 |
8 |
4 |
5 |
7 |
Answer these questions based on the research scenario and the data in this table. Remember to show all of your work. You should also attach a copy of your results from SPSS, R, Excel, Google Spreadsheets, or an online data analysis calculator. I recommend this website http://vassarstats.net/index.html. Please attach a copy of your work. If you do not have access to a scanner, please take a photo of your work and upload it with your exam.
What is the research question? What is the research hypothesis?
What is the independent variable? What is the scale of measurement for the independent variable? How many levels does the independent variable have?
What is the dependent variable? What is the scale of measurement for the dependent variable?
What is the research design? (Be specific.)
Test the null hypothesis at the .05 level of significance that there is a significant difference based on cookie color. (Perform all 7 steps of null hypothesis testing and show your work.)
Write your answers in an ANOVA summary table
The research question is the relationship between the color of food and appetite.
The independent variable is the colour of food and the scale is nominal.
There are 3 levels of the independent variable.
The dependent variable is appetite and the scale is the ratio.
The One-Way ANOVA design is valid here.
The hypothesis being tested is:
H0: µ1 = µ2 = µ3
Ha: Not all means are equal
Mean | n | Std. Dev | |||
4.2 | 6 | 1.47 | Green | ||
3.8 | 6 | 1.17 | Red | ||
6.8 | 6 | 1.72 | Blue | ||
4.9 | 18 | 1.95 | Total | ||
ANOVA table | |||||
Source | SS | df | MS | F | p-value |
Treatment | 32.44 | 2 | 16.222 | 7.49 | .0056 |
Error | 32.50 | 15 | 2.167 | ||
Total | 64.94 | 17 |
The p-value is 0.0056.
Since the p-value (0.0056) is less than the significance level (0.05), we can reject the null hypothesis.
Therefore, we can conclude that there is a relationship between the colour of food and appetite.
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