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 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.

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.

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.

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.

Two unpaired t tests . When you choose to compare the means of two non-paired groups with a t test, you have two choices: 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.

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

The paired t test assumes that you have sampled your pairs of values from a population of pairs where the difference between pairs follows a Gaussian distribution. While this assumption is not too important with large samples, it is important with small sample sizes.

You can enter data as mean, SD (or SEM) and N, and Prism can compute an unpaired t test or the Welch t test. Prism cannot perform an paired test, as that requires analyzing each pair. It also cannot do any nonparametric tests, as these require ranking the data. I only know the two group means, and don't have the raw data and don't know their SD ...