Teaching · For Teachers · Research and data

Rubric levels from
three classes, compared
without pretending.

Rubric scores of 1 to 4 are ordered, not measured, so a mean and an ANOVA claim more than the data hold. Paste each group and the calculator ranks every score, corrects for the ties that rubric data always has, and tests whether the groups differ.

Run the test What you get

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Included with Caveat Classroom and Whole-school licenses. Or get it in the For Teachers toolkit, $79 for 72 items.

The Kruskal-Wallis calculator

The worked example is made up: exit ticket rubric levels after three lesson formats. Use codes, not names. Nothing you type leaves this browser.

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What you get

Teaching · For Teachers$12 · included with Classroom and Whole-school licenses

What you finish with: H corrected for ties, degrees of freedom, the p-value, epsilon squared, each group’s median, rank sum and mean rank, and the steps. It prints as a summary and downloads as a spreadsheet.
Who it is for: Teachers doing action research, data teams and instructional leaders, school psychologists and graduate students in education.
Format: Browser calculator for a phone, tablet or computer, by touch or keyboard. Two to five groups of up to 1,000 scores. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access: $12 one-time, yours on every device you sign in on; the tool opens once you are signed in with it. Included with Caveat Classroom and Whole-school licenses. Also in the For Teachers toolkit ($79) and the Teaching Suite pass ($199), and 1 more bundle. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives: The For Teachers space in Caveat Teaching.
Support: Questions, a correction or a request: team@caveatacademic.com.

How to use it

Name the measure.
Name each group and paste its scores.
Read H and the p-value with epsilon squared and the mean ranks.
If H is significant, plan Dunn’s pairwise comparisons with a correction.
Print the summary or download the spreadsheet.

Run the test

How the test works

The rank-based one-way analysis.

With rubric levels many students tie, so ranks are shared and H is corrected for the ties. If the formats made no difference, each group’s mean rank would sit near the middle, 15.5.

When to use it

Kruskal-Wallis is the rank-based counterpart of the one-way ANOVA. It needs only that scores can be put in order, so it suits rubric levels, Likert ratings and skewed measures such as minutes or counts. With two groups it gives the same answer as a two-tailed Mann-Whitney test using the normal approximation without continuity correction.

Reading the result

A small p says at least one group tends to score differently; it does not say which. Dunn’s test, with a Holm or Bonferroni correction, compares the pairs. Report the medians and mean ranks with H. Classes are not random samples, so a gap may reflect the classes as much as the format.

Sources

Kruskal, W. H., and Wallis, W. A. (1952). Use of ranks in one-criterion variance analysis. Journal of the American Statistical Association, 47(260), 583–621.
Hollander, M., Wolfe, D. A., and Chicken, E. (2014). Nonparametric Statistical Methods (3rd ed.). Wiley. Chapter 6, the one-way layout.
Dunn, O. J. (1964). Multiple comparisons using rank sums. Technometrics, 6(3), 241–252.
Tomczak, M., and Tomczak, E. (2014). The need to report effect size estimates revisited. Trends in Sport Sciences, 1(21), 19–25.

The worked example is made up. Use student codes, not names. Your scores stay in this browser. Support: team@caveatacademic.com.

Rubric levels fromthree classes, comparedwithout pretending.