Comprehensive Calculator Guide
This calculator runs a one-way ANOVA on two to four groups: F, p-value, degrees of freedom, sums of squares, group means and effect size. Three teaching methods averaging 83.4, 89.3 and 84.7 give F = 2.36, p = 0.114: no significant difference.
Between vs within
F compares the spread of group means with the spread inside groups. A small p says some group differs; a post-hoc test such as Tukey’s says which. η² measures the size.
How to Use
- Enter groups 1 and 2.
- Add groups 3 and 4 if needed.
- Press “Run ANOVA” to see F, p and the effect size.
Formula Used
F = (SSB/(k − 1)) ÷ (SSW/(N − k)) | η² = SSB/(SSB + SSW)
Practical Examples
- Example 1
- Teaching methods: F 2.36, p 0.114.
- Example 2
- Fertilisers: F 20.67, p 0.00013.
Important Tips
- Keep group sizes similar.
- Report effect size with p.
- Plot the data first.
Common Mistakes to Avoid
- Many t-tests instead.
- Concluding all groups differ.
- Ignoring unequal variances.
Frequently Asked Questions
- When to use it?
- Three or more means.
- p below 0.05?
- Unlikely by chance.
- Degrees of freedom?
- k − 1 and N − k.