This assumes that you have columns that represent one of the variables and rows that represent the other variable. If your data is in table form, so you have summary data for each cell in the two-way table, use Chi-square analysis (two-way table in worksheet). Usually, you can just check the top box, "Chi-Square Analysis." To learn more about Tests For Two Variances, register for Black Belt Training and review Analyze Phase, Module 4.3.1. You'll need to ask for the chi-square analysis by clicking on the box labeled "chi-square analysis" and asking for the appropriate calculations. If your data is stacked so that each line of data is a separate observation, use the Cross Tabulation and Chi Square command. Minitab has produced an introductory guide. ITS has a nice set of directions to fix the problem and FAQs. If you cannot find your harddrive, then you need to fix the installation of the desktop. When you use the Virtual Desktop, your harddrive appears as $C: on Client, because your harddrive is now the client. The most common problem that people have is that they can't find their datafiles after opening Minitab. If you are using the Virtual Desktop, you must open Minitab first, then click on "Open Project" or "Open Worksheet" (depending on the file type) to find your data. You can use either Minitab 15 or 16 the price is the same, so I'd use the most recent version (16). Students can purchase a perpetual license for Minitab for $99, or rent a copy for one year. Off campus, Minitab can be accessed through the virtual desktop. Minitab is available on-campus at all University of Iowa ITCs. Minitab 16 is the current version, but the difference between 15 and 16 is minimal. 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: An important property of the t-test is its robustness against assumptions of population normality. Then, click OK to return to the main pop-up window.Minitab is a software package specifically created for statistical analysis. A t-test is a hypothesis test of the mean of one or two normally distributed populations. 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. 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 The species, the deinopis, and menneus coexist in eastern Australia. 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.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |