About One-Way ANOVA Calculator
This one-way ANOVA calculator tests whether the means of two or more independent groups are equal. It opens on test scores from three teaching techniques and shows the ANOVA table, F, the p-value and η². It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
One-way means one factor, here the group. The test asks whether the spread between the group means is larger than the spread of individuals inside the groups. If it is, F is large and p is small.
A significant result says that not all means are equal. To find which groups differ, read the Tukey HSD table that follows, or use the dedicated Tukey page.
How to use One-Way ANOVA Calculator
- Paste your data with one group per column. A text first row names the groups. Use "Groups in rows" if your groups run across the page.
- Choose the significance level α, usually 0.05.
- Read the ANOVA table: F is the ratio of between-group to within-group variance, and p says how surprising that ratio is if all group means were equal.
- If p is below α, read the Tukey HSD table to see which pairs of groups differ.
- Check the group statistics and the box plots. Very different spreads or heavy outliers weaken the test.
- Copy the summary line for your report.
Features
- One-way ANOVA table with SS, df, MS, F and p.
- Effect size η², the share of the total variance that is between groups.
- Tukey HSD post-hoc test for every pair, with Tukey-Kramer for unequal group sizes.
- Group sizes, means and standard deviations.
- Box plots by group with whiskers and outliers.
- Paste columns straight from a spreadsheet, with blank cells for uneven groups.
- Plain-English reading of the result.
- Three bundled examples to try.
Worked examples
Three techniques with 10 scores each gives F(2, 27) = 2.358, p = 0.114
η² = 0.149, so the technique explains 14.9% of the variation in scores. Means: 83.4, 89.3, 84.7.
Privacy: how it works
- Everything is calculated by code running in your browser tab. Your data is not sent to Ulkaa or to any other server, and there is nothing to sign in to.
Tips
- With only two groups, ANOVA gives the same p-value as a two-sided t test with equal variances, and F equals t squared.
- Do not run many separate t tests on the same groups. The chance of a false positive grows, which is the problem Tukey HSD solves.
- Report F with both degrees of freedom, the p-value and η², for example F(2, 15) = 9.26, p = 0.002, η² = 0.55.
- Make sure each column is a different group of independent people or items, not the same people measured repeatedly.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Your data are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Your data are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
How do I do a one-way ANOVA in Excel or Google Sheets?
Put each group in its own column, copy the block and paste it here. The calculator returns the same table as the Excel ANOVA single factor tool.
What is the null hypothesis?
That every group has the same population mean.
What is the difference between ANOVA and a t test?
A t test compares two means. ANOVA compares three or more in one test, which avoids the extra false positives of running many t tests.