Paired t-Test Calculator
Compare paired measurements such as before-and-after values by testing the mean of the within-pair differences.
Formula / method
t = d̄/(s_d/√n), df = n−1.
How to use
Use data from the same population, sample or study definition and keep paired observations aligned.
Understanding a paired t test
A paired t test analyzes the within-pair differences, making it appropriate for before/after measurements or intentionally matched observations. It is not the same as treating the two columns as independent samples.
Interpretation
A small p-value indicates evidence that the population mean difference differs from the null value, subject to the pairing and model assumptions.
What this calculator answers
The Paired t-Test Calculator uses the requested values to calculate the requested result. The core method is t = d̄/(s_d/√n), df = n−1.. This makes the assumptions visible so you can check whether the inputs match your situation.
How to get a useful result
Use data from the same population, sample or study definition and keep paired observations aligned.
How to interpret it
Statistical output describes the entered sample/model. It does not by itself prove causation, practical significance or that model assumptions are satisfied.
Before relying on the number
Recheck unusual inputs, confirm units and compare the result with any official quote, statement, specification or rule that applies to the real decision. Small changes in rates, time periods or measurements can materially change some results.