The null hypothesis in single factor ANOVA is that the means of the various samples are equal.
Each of the following four columns (stored in the waves f1to f4) represents instrument recording of some arbitrary property consisting of 6 samples.
Sample | f1 | f2 | f3 | f4 |
1 | 19 | 22 | 20 | 21 |
2 | 21 | 21 | 22 | 19 |
3 | 19 | 20 | 20 | 22 |
4 | 20 | 22 | 22 | 19 |
5 | 19 | 22 | 21 | 20 |
6 | 18 | 19 | 20 | 18 |
H0: there is no difference in the values recorded by the four instruments.
Ha: there is sufficient difference in the values recorded by the four instruments.
To run the test, execute the following command:
StatsAnova1Test/T=1/Q/W/BF f1,f2,f3,f4
The results are displayed in three tables. Straight ANOVA results are in the table "ANOVA1 Results":
DF | SS | MS | F | Fc | P | ||
Groups | 3 | 11.5 | 3.83333 | ||||
Error | 20 | 29 | 1.45 | ||||
Total | 23 | 40.5 | 1.76087 | 2.64368 | 3.09839 | 0.077207 |
Here the critical value Fc>F so H0 can't be rejected. Note also that P>alpha which is set by default to 0.05.
The second table titled "Welch Test" contains the following results:
N1 | 3 |
N2 | 8 |
Fp | 0.45153 |
Fpc | 4.06618 |
Pp | 0.723258 |
Here Fp is the Welch test statistic associated with degrees of freedom N1 and N2, Fpc is the critical value and Pp is the P-value.
The third table "Brown and Forsythe Test" contains the following results:
N1 | 3 |
N2 | 18 |
Fp | 2.64368 |
Fpc | 3.15991 |
Pp | 0.0805162 |
Here again Fp is the test statistic associated with degrees of freedom N1 and N2, Fpc is the critical value and Pp is the P-value.
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