Performs unpaired t test, Weldh's t test (doesn't assume equal variances) and paired t test. Calculates exact P value and 95% confidence interval. Clear results with links to extensive explanations.

Unpaired samples t test, also called independent samples t test, is appropriate when you have two sample groups that aren’t correlated with one another. A pharma example is testing a treatment group against a control group of different subjects.

The unpaired t test works by comparing the difference between means with the standard error of the difference, computed by combining the standard errors of the two groups. If the data are paired or matched, then you should choose a paired t test instead.

The unpaired t test compares the means of two groups. Note that this test is often called independent samples t test. The most useful result is the confidence interval for the difference between the means.

Prism offers seven related tests that compare two groups. To choose among these tests, answer three questions in the Experimental Design tab of the t test parameters dialog: Experimental design: unpaired or paired. Choose a paired test when the columns of data are matched. That means that values on the same row are related to each other.

The unpaired t test compares the means of two unmatched groups, assuming that the values follow a Gaussian distribution.

We recommend plotting the mean and SD if you analyze with an unpaired t test, and the median and Interquartile range if you use the nonparametric Mann-Whitney test. • If you choose a bar graph, don't use a log scale on the Y axis.

Use the standard unpaired t test. It assumes that both groups of data are sampled from Gaussian populations with the same standard deviation . Use the unequal variance t test , also called the Welch t test .

Navigation: STATISTICS WITH PRISM 10 > t tests, Mann-Whitney and Wilcoxon matched pairs test > Unpaired t test. How to: Unpaired t test from raw data

How the ratio t test calculations work. 1. Transform all the values to their logarithm: Y=log(Y). 2. Perform a paired t test on the logarithms. 3. The antilogarithm of the difference between logarithms is the geometric mean of the ratios. 4. Calculate the antilogarithm of each confidence limit of the difference between the means of the logarithms.