Biostats Calculator

Features > Paired t-test

A paired t-test is used when two measurements have been made of the same subjects, and we want to know whether there is a significant difference between these measurements on average. For example, subjects could be measured before and after a treatment, in an attempt to determine whether the treatment produces an improvement.

After selecting Paired t-test from the menu, simply enter the sample values for each individual. Biostats Calculator will calculate the difference between measurements and perform a hypothesis test to determine whether it is statistically significant.

Biostats Calculator reports:

• The mean and standard deviation the first and second samples
• The mean and standard deviation of the difference between the samples
• Confidence intervals for the mean difference, at the 90%, 95% and 99% confidence levels
• The t statistic and degrees of freedom, which together describe the magnitude of variation between samples
• The p value, indicating how likely it is that the observed difference would occur due to chance alone
• whether the result is significant at the 95% confidence level

Biostats Calculator can perform this test and 11 others from the convenience of your iPhone or iPod Touch. Buy it today!

Related tests

• Unpaired t-test - for comparing independent samples of two groups
• Wilcoxon signed-rank test - a non-parametric test for data that are not normally distributed