One-sample t Test

A one-sample t-test is used to test whether the mean for a variable has a particular value. The main assumption in a t-test is that the data comes from a Gaussian (normal) distribution. If this is not the case, then a nonparametric test, such as the Wilcoxon signed-rank test, may be a more appropriate test of location.

To perform one-sample t test

Choose Statistics __image\ebd_ebd8.gif Compare Samples __image\ebd_ebd9.gif One Sample __image\ebd_ebd10.gif t Test. The dialog shown below appears.

__image\ttest.gif

The One-Sample t Test dialog has the following options:

Data

Data Set

Select a data set from the dropdown list or type the name of a data set. You can also type into the Data Set edit field any expression that evaluates to a data set.

Variable

Select the column to which the test will be applied.

Hypotheses

Mean Under Null Hypothesis

Enter the difference between the assumed population means of Variable x and Variable y.

Alternative Hypothesis

Specify the alternative hypothesis. For example, to perform a one-sided test against the alternative hypothesis that the mean of Variable 1 is greater than the mean of Variable 2, select greater from the list box.

Confidence Interval

Confidence Level

Enter a number between 0 and 1 to be used as the confidence level.

Results

Save As

Enter the name for the object in which to save the results of the analysis.

Print Results

Select this to print out the results of the analysis in the designated output window.

Related S-PLUS language functions:

t.test