Teaching · For Teachers · Research and data

Did the same
students really
move?

Paste fall and winter scores in the same order. The calculator works out each student’s change, tests whether the average change stands out from the noise, and shows who went up and who did not.

Test the changeWhat you get
$12one-time · every device you sign in on
Buy · $12

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

The paired t-test calculator

The worked example is made up: ten students’ oral reading fluency in September and January. 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
The mean change with its confidence interval, t, degrees of freedom, the two-tailed p-value and dz, every pair with its change, and how many went up, down or stayed. It prints as a summary and downloads as a spreadsheet.
Who it is for
Teachers doing action research, reading and math interventionists, data teams and graduate students in education.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Up to 2,000 pairs. 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

  1. Name the measure and the two occasions.
  2. Paste the first scores, then the second scores in the same student order.
  3. Choose a confidence level.
  4. Read the mean change and its interval, then the pairs that went down.
  5. Print the summary or download the spreadsheet.

Test the change

How the paired test works

One list of changes, tested against zero.

The worked example: test the changes, not the two listsTen changes+6.1 avgJanuary − SeptemberSpread of changesSD 3.84how much students differStandard error1.223.84 ÷ √10t and p5.02p < .001, df 9The worked example: test the changes, not the two listsTen changes+6.1 avgJanuary − SeptemberSpread of changesSD 3.84how much students differStandard error1.223.84 ÷ √10t and p5.02p < .001, df 9
Pairing removes the differences between students: the test looks only at each student’s change, which averages +6.1 words correct per minute.

Why pairing matters

A paired test subtracts each student’s first score from their second and tests whether the average of those changes differs from zero. Because each student is compared with themselves, the large differences between students drop out, and a modest but consistent change can be detected with a small group. Running an independent test on the same data throws that advantage away.

What it cannot tell you

A reliable change is not proof that the program caused it. Students grow over a school year, tests given twice show practice effects, and very low first scores tend to rise on retest. A comparison group, or typical growth rates for the measure, is what separates the program’s contribution from those.

Sources

  1. NIST/SEMATECH e-Handbook of Statistical Methods, section 1.3.5.3 and 7.3: t-tests for paired data (itl.nist.gov).
  2. Lakens, D. (2013). Calculating and reporting effect sizes to facilitate cumulative science. Frontiers in Psychology, 4, 863: dz for paired designs.
  3. Institute of Education Sciences, What Works Clearinghouse. Procedures and Standards Handbook, Version 5.0 (2022): why pre-post designs without a comparison group do not establish effects.
  4. Glass, G. V., and Hopkins, K. D. (1996). Statistical Methods in Education and Psychology (3rd ed.). Allyn and Bacon: the t-test for dependent samples.

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