Then, click OK to return to the main pop-up window. In the pop-up window that appears, for the box labeled Alternative, select either less than, greater than, or not equal depending on the direction of the alternative hypothesis: (For Welch's t-test, leave the box labeled Assume equal variances unchecked.):Ĭlick on the button labeled Options. For the two-sample (pooled) t-test, click on the box labeled Assume equal variances. Specify the name of the Samples variable (Prey, for us) and specify the name of the Subscripts (grouping) variable (Group, for us). In the pop-up window that appears, select Samples in one column. As explained on this short tutorial on Minitab 2-Sample-t-test, any scheme can be used by filling out the correct option in the 2-Sample-t dialog box. Under the Stat menu, select Basic Statistics, and then select 2-Sample t.:
Let's use the data and Minitab to test whether the mean prey size of the populations of the two types of spiders differs.Įnter the data in one column (called Prey, say), and the grouping variable in a second column (called Group, say, with 1 denoting a deinopis spider and 2 denoting a menneus spider), such as: Size of Random Pray Samples of the Menneus Spider in Millimeters sample 1 The following data were obtained on the size, in millimeters, of the prey of random samples of the two species: Size of Random Pray Samples of the Deinopis Spider in Millimeters sample 1 Tests whether the mean of a single population is equal to a target value. Several types of t-tests exist for different situations, but they all use a test statistic that follows a t-distribution under the null hypothesis: Test.
The species, the deinopis, and menneus coexist in eastern Australia. A t-test is a hypothesis test of the mean of one or two normally distributed populations. Let's recall the spider and prey example, in which the feeding habits of two species of net-casting spiders were studied. Just as is the case for asking Minitab to calculate pooled t-intervals and Welch's t-intervals for \(\mu_1-\mu_2\), the commands necessary for asking Minitab to perform a two-sample t-test or a Welch's t-test depend on whether the data are entered in two columns, or the data are entered in one column with a grouping variable in a second column.
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