Paired t-test
Before and after, in the same people.
When should I use Paired t-test?
The same participants were measured twice, so the two measurements are linked. A paired t-test uses that pairing, which makes it more sensitive than treating the measurements as separate groups.
What your data needs to look like
Two sets of measurements.
What Paired t-test assumes
Chavery checks each of these against your data before it runs the test, and says whether it held. It does not ask you to assert them.
- Normality (Shapiro-Wilk)
- The values are spread roughly symmetrically around their average, rather than bunched at one end or dominated by a few extreme readings. When this one fails, Chavery runs Wilcoxon signed-rank instead.
What Chavery offers instead, and when
- Wilcoxon signed-rank — when normality does not hold.
What Chavery does with it
It checks the assumptions first and says whether each one held. When an assumption fails it names the alternative test rather than running this one anyway.
Then it reports the statistic, the p-value, a confidence interval and an effect size, and writes the sentence you would put in your results chapter. The same numbers always give the same answer; nothing is generated by a language model.
Reporting it
A p-value on its own is not a result. Chavery reports the effect size beside it, because a difference can be statistically significant and too small to matter, and an examiner will ask which yours is. More on effect size.
Not sure this is the test you need? Work through the question Chavery asks and it will name the test your design calls for.
Related tests
- Independent t-test — Do two separate groups differ on average?
- Kruskal-Wallis — Three or more groups, without assuming normality.
- Mann-Whitney U — Two groups, without assuming normality.
- One-sample t-test — Is this group's mean different from a known value?
- One-way ANOVA — Three or more groups.
- Welch's t-test — Two groups with unequal spread.
- Wilcoxon signed-rank — Before and after, without assuming normality.
Run it on your own data. Paste your numbers and Chavery runs Paired t-test with the assumption checks and the reported sentence — no project needed. Open the analysis tool, or let Chavery choose the test for you.