statistic
giumag
Ch_11_in_Excel.pptChapter 11 ANOVA
Statistical Functions in Excel
MTH 305 Statistics
*
Example: 3 Groups
*
We want to test whether study time before an exam differs between 3 groups of SSU students: Newport Beach, San Diego, and Las Vegas
Y: study exam time (in hours)
X: SSU Group (NB, SD, LV)
n = 30 students
c = 3 groups
Y is the dependent variable
X is the independent variable
H0: µ1 = µ2 = µ3
(study time is the same)
H1: µ1 ≠ µ2 ≠ µ3
(study time differs)
| Student ID | SSU NB | SSU SD | SSU LV |
| 1 | 3 | 5 | 1 |
| 2 | 2 | 9 | 0 |
| 3 | 2.5 | 3 | 0 |
| 4 | 4 | 10 | 2 |
| 5 | 10 | 10 | 0.5 |
| 6 | 0 | 6.5 | 1 |
| 7 | 8 | 2 | 2 |
| 8 | 8 | 7 | 1 |
| 9 | 1 | 7 | 1 |
| 10 | 3 | 4 | 1 |
Make sure your data is together and is arranged by having one column for each group.
Under the DATA tab in Excel:
Data Analysis
ANOVA Single Factor
Select the data range of the three groups with the mouse (include the title of the columns), select “column” under “Group by”, place a check mark under “Labels in First Row”, use an alpha value of 0.05 for a 95% confidence level, and click OK.
*
*
Excel Output of ANOVA test
F statistic
F critical
*
Conclusion of Excel Output
Because F-statistic > F-critical it means that we will reject the Null:
11.23 < 3.35 reject Null and conclude that we are 95% confident that these three groups do NOT spend the same amount of time studying on average.
*
Anova: Single Factor
SUMMARY
Groups
Count
Sum
Average
Variance
SSU NB
10
41.5
4.15
11.225
SSU SD
10
63.5
6.35
8.002778
SSU LV
10
9.5
0.95
0.469444
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Between Groups
147.4667
2
73.73333
11.23001
0.000282
3.354131
Within Groups
177.275
27
6.565741
Total
324.7417
29
