Factorial Analysis of Variance in Relation to Professional Athletes’ Healthy Eating Habits
A sports psychologist gave a questionnaire about healthy eating habits to randomly selected professional athletes. The results are displayed below. Using the .05 significance level, is there a difference in healthy eating habits among professionals in the three sports?
Baseball Players Basketball Players Football Players
32 27 27
27 36 23
26 25 26
35 30 20
- Make a graph for the data set.
Answer
Use the five steps of hypothesis testing (report results in APA format).
Step1: Null and Alternative hypothesis
At 5% level of significance
Step 2: Test Statistics
To test the hypothesis analysis of variance (ANOVA) test will be performed.
Anova: Single Factor |
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SUMMARY |
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Groups |
Count |
Sum |
Average |
Variance |
Baseball Players |
4 |
120 |
30 |
18 |
Basketball Players |
4 |
118 |
29.5 |
23 |
Football Players |
4 |
118 |
29.5 |
23 |
ANOVA |
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Source of Variation |
SS |
df |
MS |
F |
P-value |
F crit |
Between Groups |
0.666667 |
2 |
0.333333 |
0.015625 |
0.984523 |
4.256495 |
Within Groups |
192 |
9 |
21.33333 |
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Total |
192.6667 |
11 |
Step 3: Critical value
We find the critical value at 5% level
Step 4: Decision
The null hypothesis is rejected if the computed F value is greater than the F-critical value otherwise the null hypothesis is accepted.
Step 5: Conclusion
The computed F-value (0.0156) is less than the F-critical (4.2565) hence the null hypothesis is not rejected as such we conclude that there is no significant difference in healthy eating habits among professionals in the three sports.
Effect size output
The overall effect size f = 0.0510
The effect size for Group 1 vs Group 2 is f = 0.0442
The effect size for Group 1 vs Group 3 is f = 0.0442
The effect size for Group 2 vs Group 3 is f = 0.0000
- Conduct a planned contrast for Baseball versus Football players (using Tukey’s HSD).
Answer
Multiple Comparisons |
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Dependent Variable: VAR00001 |
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Tukey HSD |
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(I) VAR00002 |
(J) VAR00002 |
Mean Difference (I-J) |
Std. Error |
Sig. |
95% Confidence Interval |
|
Lower Bound |
Upper Bound |
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Baseball |
Basketball |
.50000 |
3.26599 |
.987 |
-8.6187 |
9.6187 |
Football |
.50000 |
3.26599 |
.987 |
-8.6187 |
9.6187 |
|
Basketball |
Baseball |
-.50000 |
3.26599 |
.987 |
-9.6187 |
8.6187 |
Football |
.00000 |
3.26599 |
1.000 |
-9.1187 |
9.1187 |
|
Football |
Baseball |
-.50000 |
3.26599 |
.987 |
-9.6187 |
8.6187 |
Basketball |
.00000 |
3.26599 |
1.000 |
-9.1187 |
9.1187 |
Results of the post-hoc Tukey HSD showed that there is no significant difference in healthy eating habits between the Baseball and football players.
- (25 points) A researcher is interested in the effects of sleep deprivation and caffeine intake on mood. Participants were randomly assigned to a sleep condition (normal or deprived) and a caffeine condition (0 cups, 2 cups, or 4 cups). After the manipulations, mood was measured (such that higher numbers indicated better mood). The results were as follows:
Normal Condition Deprived Condition
0 cups 2 cups 4 cups 0 cups 2 cups 4 cups
16 18 18 0 5 6
17 20 17 6 4 8
20 20 17 3 4 6
19 19 17 2 2 7
18 18 16 4 5 8
Analyze these data using a factorial analysis of variance and including R2 for each effect.
Answer
Tests of Between-Subjects Effects |
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Dependent Variable: mood score |
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Source |
Type III Sum of Squares |
df |
Mean Square |
F |
Sig. |
Partial Eta Squared |
Corrected Model |
1386.667a |
5 |
277.333 |
144.696 |
.000 |
.968 |
Intercept |
3853.333 |
1 |
3853.333 |
2010.435 |
.000 |
.988 |
Caffeine |
11.667 |
2 |
5.833 |
3.043 |
.066 |
.202 |
Sleep |
1333.333 |
1 |
1333.333 |
695.652 |
.000 |
.967 |
Caffeine * Sleep |
41.667 |
2 |
20.833 |
10.870 |
.000 |
.475 |
Error |
46.000 |
24 |
1.917 |
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Total |
5286.000 |
30 |
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Corrected Total |
1432.667 |
29 |
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a. R Squared = .968 (Adjusted R Squared = .961) |
Results shows that there was a statistically significant two-way interaction between Caffeine and Sleep, F(2, 24) = 10.87, p = .000.
The value of R-Squared is 0.968; this implies that the two factors (caffeine and sleep conditions) together with their interaction explain 96.8% of the variation in the mood score.
- (25 points) A researcher was interested in whether college GPA (X) would predict starting salary after college (Y). (For simplicity, salary was converted to a 100-point scale.) The participants’ scores were:
X Y
2.25 55
1.75 23
3.25 80
3.75 42
M = 2.75 M = 50
- Report the correlation and linear prediction equation.
Answer
Correlation
X |
Y |
|
X |
1 |
|
Y |
0.48065 |
1 |
The correlation coefficient between x and y is 0.4807; this implies a weak positive correlation between the two variables (X and Y).
Linear prediction equation;
- Make a graph with the regression line.
Answer
Coefficientsa |
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Model |
Unstandardized Coefficients |
Standardized Coefficients |
t |
Sig. |
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B |
Std. Error |
Beta |
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1 |
(Constant) |
15.350 |
46.511 |
.330 |
.773 |
|
x |
12.600 |
16.255 |
.481 |
.775 |
.519 |
|
a. Dependent Variable: y |
The standardized regression coefficient is 0.481.
- (25 points) An advertising firm wanting to target people with strong desires for success conducted a study to see if such people differed in the types of television shows they watched. Randomly selected participants recorded the shows they watched for a week, then their desire for success was assessed, and finally they were divided into two groups. Low Success seekers watched 8 comedies, 15 romances, 6 documentaries, 13 dramas, and 3 news shows. High Success seekers watched 3 comedies, 3 romances, 9 documentaries, 7 dramas, and 8 news shows. Using the .05 significance level, is the distribution of type of shows watched different for participants having high and low desires for success?
Low Success seekers |
High Success seekers |
Total |
|
Comedies |
8 |
3 |
11 |
Romances |
15 |
3 |
18 |
Documentaries |
6 |
9 |
15 |
Dramas |
13 |
7 |
20 |
News shows |
3 |
8 |
11 |
Total |
45 |
30 |
75 |
Use the five steps of hypothesis testing.
Answer
Step1: Null and Alternative hypothesis
H0: There is no significant association between desire for success and type of television shows watched
HA: There is significant association between desire for success and type of television shows watched
At 5% level of significance
Step 2: Test Statistics
To test the hypothesis Chi-Square test of association will be performed.
Results |
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Low Success seekers |
High Success seekers |
Row Totals |
|
Comedies |
8 (6.60) [0.30] |
3 (4.40) [0.45] |
11 |
Romances |
15 (10.80) [1.63] |
3 (7.20) [2.45] |
18 |
Documentaries |
6 (9.00) [1.00] |
9 (6.00) [1.50] |
15 |
Dramas |
13 (12.00) [0.08] |
7 (8.00) [0.12] |
20 |
News shows |
3 (6.60) [1.96] |
8 (4.40) [2.95] |
11 |
Column Totals |
45 |
30 |
75 (Grand Total) |
The chi-square statistic is 12.4432. The p-value is .014343.
Step 3: Critical value
We find the critical value at 5% level
Step 4: Decision
The null hypothesis is rejected if the computed Chi-Square value is greater than the critical Chi-Square value otherwise the null hypothesis is accepted.
Step 5: Conclusion
The computed Chi-Square value (12.4432) is greater than the critical Chi-Square value (9.4877) hence the null hypothesis is rejected as such we conclude that there is significant association between desire for success and type of television shows watched.